Reading Essentials an Interactive Student Textbook Fl7.Msscience.Com Glencoe Science to the Student

Reading Essentials An Interactive Student Textbook fl7.msscience.com Glencoe Science To the Student

In today’s world, knowing science is important for thinking critically, solving problems, and making decisions. But understanding science sometimes can be a challenge. Reading Essentials takes the stress out of reading, learning, and understanding science. This book covers important concepts in science, offers ideas for how to learn the information, and helps you review what you have learned. In each chapter: • Before You Read sparks your interest in what you’ll learn and relates it to your world. • Read to Learn describes important science concepts with words and graphics. Next to the text you can find a variety of study tips and ideas for organizing and learning information: • The Study Coach offers tips for getting the main ideas out of the text. • Foldables™ Study Organizers help you divide the information into smaller, easier- to-remember concepts. • Reading Checks ask questions about key concepts. The questions are placed so you know whether you understand the material. • Think It Over elements help you consider the material in-depth, giving you an opportunity to use your critical-thinking skills. • Picture This questions specifically relate to the art and graphics used with the text. You’ll find questions to get you actively involved in illustrating the concepts you read about. • Applying Math reinforces the connection between math and science. • Use After You Read to review key terms and answer questions about what you have learned. The Mini Glossary can assist you with science vocabulary. Review questions focus on the key concepts to help you evaluate your learning. See for yourself. Reading Essentials makes science easy to understand and enjoyable.

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ISBN 0-07-872595-x Printed in the United States of America 1 2 3 4 5 6 7 8 9 10 047 09 08 07 06 05 Table of Contents

To the Student ...... ii Chapter 1 The Nature of Science and Technology ...... 1 Chapter 2 Properties and Changes of Matter ...... 19 Chapter 3 Inside the Atom ...... 29 Chapter 4 Forces and Changes in Motion ...... 43 Chapter 5 Work and Simple Machines ...... 59 Chapter 6 Energy and Energy Resources ...... 73 Chapter 7 Waves, Sound, and Light ...... 93 Chapter 8 Rocks and Minerals ...... 113 Chapter 9 Clues to Earth’s Past ...... 131 Chapter 10 Earth’s Place in Space ...... 153 Chapter 11 Cells ...... 175 Chapter 12 Classifying Plants ...... 189 Chapter 13 Plant Processes ...... 203 Chapter 14 Classifying Animals ...... 213 Chapter 15 Animal Behavior ...... 231 Chapter 16 The Nonliving Environment ...... 241 Chapter 17 Conserving Life ...... 255 Chapter 18 Our Impact on Land ...... 267 Chapter 19 Our Impact on Water and Air ...... 281 Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

iii chapter The Nature of Science 31 and Technology

section ●1 What is science? Benchmarks—SC.H.1.3.1 Annually Assessed: The student knows that scientiﬁc knowledge is subject to modiﬁcation . . .; SC.H.1.3.4 Annually Assessed: The student knows that accurate record keeping, openness, and replication are essential to maintaining credibility . . .; Also covers: SC.H.1.3.2; SC.H.1.3.3; SC.H.1.3.4 SC.H.1.3.5; SC.H.1.3.6; SC.H.1.3.7; SC.H.3.3.5; SC.H.3.3.7

Before You Read What You’ll Learn ■ how science is part of How do you ﬁnd answers to questions about what is everyday life happening around you? ■ skills and tools used in science

Read to Learn Study Coach Ask Questions Read each Scientific Inquiry subhead. Then work with a partner to write questions What do you think of when you hear the word science? about the information in each Do you think only about your science class or your science subhead. Take turns asking and book? Is there any connection between what you learn in answering the questions. Use science class and the rest of your life? When you have the questions as a study guide. problems to solve or questions to answer, you can use science. Science is a systematic process that helps you ask questions about the world around you. A scientist is a person who works to learn more about the natural world. When did people first use science? People have always tried to find answers to questions about what was happening around them. Early scientists tried to explain things based on what they observed using ●A Describe Make a two-tab their senses—sight, touch, smell, taste, and hearing. But, book, as shown below. Use the using only your senses can be misleading. How heavy is Foldable to describe tools scientists use and skills they heavy? What is cold or hot? develop. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Today, scientists use numbers to describe observations. Tools such as thermometers add numbers to descriptions. Science Science Like scientists, you can observe, investigate, and experiment Tools Skills to find answers.

Reading Essentials 1 2. 1. 2 Analyze Predict and similarity betweencholera scientists inthefuture? invented toolcouldhelp The NatureofScience andTechnology E. coli ? What recently What isone assignment and learn more and learn aboutscience.assignment realize helpthem completeThey thatthiswill ahistory project. theirhistory plan to compare of theresults aspart the today thesource down are tracking of alsowantto They know how scientists in1871. cholera the decide to findout how peoplediscovered thesource of contaminated foodorwater. cure human illnesses. ledto microbiology newways to study and the study of Over time, scientificstudy microbiology. called new fieldof created His a observation microscope to bacteria. observe He usedthe thefirstmicroscopes inthe1670s. built oneof Antonie vanLeeuwenhoek For example, developed. theories may Existingtheories bechallenged andnew observations. ideas change asscientists usenewtools andmake new Scientific tools helpscientistsmake newobservations. problems. coli E. become dehydrated andsomemay die. causesbadcasesof Cholera sick. get they When thiswater, drink people contaminated water. live Thebacteria in is adiseasecausedby abacterium. and an in 1871with decidetoMidori compare outbreak andcontrast acholera Luis and somethingthatishappeningtoday. event with Theirtaskisto compare andcontrast apast project. history around us. lookforpatterns to They helpexplain theworld world. All scientistsaskquestionsaboutthenatural thinking. of scientistsshare all similarways However, scientific questions. study usesdifferent tools andmethodsto findanswers to What causeschangesinscientificideas? Science asaTool What doallscientistshaveincommon? usadMdr nwte edt er oe They Luis know andMidori needto more. they learn e ol r en netdeeyya.Sm fthese of Some New tools are beinginvented year. every .coli E. Luis know firstlistwhatthey andMidori aboutcholera are working ona Luis andMidori, Suppose two students, Each fieldof study. Science hasmany different fieldsof .coli E. do not harm people, but some types causeintestinal butsometypes people, do notharm is another type of bacterium. Some types of Sometypes bacterium. of is anothertype . They learned intheirscience learned classesthatcholera They . .coli E. .coli E. that makes humans illisfound in outbreak happening now. irha People quickly diarrhea. .coli E. .They

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. the necessary information. necessary the andweb pagesthathave videos, newspapers, magazines, You canusethecomputer to findbooks, materials. like gravity. apattern innature, thatdescribe rules are These laws. Scientistsalsoform by facts. that issupported isanexplanation A theory predictions have beenwell tested. whentheir theories Scientiststhenform predictions. occurpredict in whatwill orpunctuation. use incorrect grammar they losepointsif canpredict will they thatthey experiences, ontheirpast Based haveand Midori from learned experience. Luis which helostpointsforincorrect spellingandgrammar. Luis project remembers on hislasthistory However, sheet. Theteacher didnotstate ontheassignment thisrule elements. andpunctuationalsoarethat correct important grammar the Internet. or videotapes, letters, different sources articles, such aswritten Information must come from andgraphs. orcharts pictures, mustThe report bethree pageslongandmust includemaps, thing by cluesto following findthesource of scientistsdothesame Today, outbreak. thecholera sources of People in1871followed the cluesto track the samething. scientistsdo In many ways, skills andtools to findtheclues. useseveral will They how two events are similaranddifferent. Luis lookforcluesthatshow andMidori problem to solve. make decisions. day you to canusescientificthinkingevery In fact, science. you are using forexample, research class, foryour history Using ScienceandTechnology How doscientistsusepriorexperience? Using PriorKnowledge What cluesdoscientistsuse? Day Using ScienceEvery o gtifrain o edavreyo resource of you needavariety To getinformation, experience to useprior They Scientists dothesamething. reminds Midori Luis Luis discusstheproject. andMidori Luis knows thattheproject must requirements. meetcertain you have a When you have aproject class, to doforhistory When you are doing You usescience indifferent ways. vestigations. They test They their vestigations. .coli E. . 3. Explain Reading Essentials What isatheory? 3 Computers The computer is one tool that modern scientists use to find and analyze data. Computers help scientists collect, sort, and analyze data. Computers also make it easier for scientists to prepare research reports and to share data and ideas with each other. What is technology? Modern scientists use computers to find and analyze data. The computer is a kind of technology. Technology is the application of science to make products or tools that people can use. Luis and Midori learn that the use of technology is one big difference between the way diseases were tracked in 1871 and the way they are tracked today. Computer technology helps scientists in many ways. Scientists use computers to research scientific questions on the Internet. They build spreadsheets and databases to sort and analyze data. Word processing, graphics, and multimedia software help scientists share their research 4. Identify three ways findings with others. The more familiar you become with scientists use computers. computer technology, the easier it will be to use computers in your investigations. What skills do scientists use? Scientists use skills such as observing, classifying, and interpreting data. You use these skills when you solve problems or run experiments. Luis and Midori learned that scientists in 1871 used these skills to track the source of the cholera outbreak. Likewise, scientists use them today to track the source of E. coli. Why are observation and measurement skills important? Observing, measuring, comparing, and contrasting are important skills for learning. Scientists often use these skills in their work. Observations are important, but sometimes they do not give a complete picture of what is happening. It is important to take accurate measurements to be sure that your data are useful. 6. Synthesize Name an Luis and Midori want to find the similarities and observation you have made differences between the ways diseases were tracked in the

in the last week. 1870s and the way they are tracked today. They will use Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright their comparing and contrasting skills. They will look for similarities to compare the disease-tracking methods. Contrasting the methods means looking for the differences.

4 The Nature of Science and Technology Communication in Science The work of scientists is most useful when it is shared with others. After scientists get the results of their observations, experiments, and investigations, they use several methods to share their observations with others. Results and conclusions of experiments often are reported in the many scientific journals or magazines that are published each year. Scientists use scientific publications to learn about the 6. Explain one way latest research. Scientists send papers to journals. Other scientists communicate scientists review them before they are published. their research. What is the purpose of a science journal? Keeping a science journal is another way of communicating scientific data and results. A journal can be used to record observations and the step-by-step procedures that were followed. The journal can be used to list the materials and equipment that were used. It can include the results of an investigation. Your journal, like the one below, should include mathematical measurements or formulas that were used to analyze the data. Include any problems that happened during the investigation. You might summarize the data in a paragraph or by using tables, charts, or graphs.

Picture This 7. Explain one way you might use a science journal.

Reading Essentials 5 3. 2. 1. scientist: science: Mini Glossary 6 about science? How questionshelp you didaskingandanswering remember you what have learned Complete by listingtheskillsthatscientistsneedto thediagram dotheirwork. awaydescribes intheirwork. scientistsusetechnology Write asentence that Review theterms andtheirdeﬁnitionsintheMini Glossary. After You Read Section about theworldaroundyou world End of The NatureofScience andTechnology a systematicprocessthathelpsyouaskquestions a personwhoworkstolearnmoreaboutthenatural Skills ScientistsNeed and projectstohelpyoulearnmore aboutwhatscienceis. Visit ﬂ7.msscience.com technology: tools thatpeoplecanuse the applicationofsciencetomakeproductsor to accessyourtextbook,interactive games,

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. through observation. design. ways are descriptive research research andexperimental answered before thesecond problem canbeinvestigated. must be thedisease, finding thesource of problem, first The thediseaseisknown. disease untilthesource of ascientistcannotfindcure fora For example, addressed. problem must besolved before anotheronecanbe Sometimesone theproblem. has aclearunderstandingof have to make sure working thateveryone to solve theproblem scientistsusesomesteps inallinvestigations. However, investigations. different andrequire different kindsof problems are of Thetypes work to solve scientificproblems. scientists Every day, scientificproblems. of This alsoistrue How can the problem besolved? How cantheproblem What isthefirststepinaninvestigation? Solving Problems would you solve thisproblem? How but you leftyour bookatschool. is duetomorrow, You need your science bookto complete that anassignment section cetfi rbescnb ovdi ifrn as Two Scientific problems canbesolved indifferent ways. They The firstthingscientistsdoisidentifytheproblem. You know there ismore thanoneway to solve aproblem. chapter Read toLearn YouBefore Read 3 Also covers: maintaining aninvestigator’scredibilitywithotherscientistsandsociety. Benchmarks—SC.H.1.3.2; SC.H.1.3.4AnnuallyAssessed: 1 Descr ● 2 SC.H.1.3.1; SC.H.1.3.5;SC.H.1.3.6;SC.H.1.3.7;SC.H.3.3.5 ip and Technology The NatureofScience t Doing Science i v e r ese ar c h answers scientificquestions The studentknowsthataccuraterecordkeeping,openness,andreplicationareessentialto ● the section. when youhavefinishedreading paragraph. Reviewtheseideas Underline themainideaineach Identify theMainIdea and theirdefinitions. vocabulary wordsinthissection Foldable torecordthe book asshownbelow.Usethe B What You’llLearn ■ ■ Define developed investigation is how awell-designed way a probleminscientific the stepsusedtosolve

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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. clearly defined. An An clearly defined. cause andeffectrelationships. It focuses on acontrolled situation. questions by observing research Experimental answers scientific experimentation. descriptive research. andexperimental of parts important dataare Analyzing andsharing thatshow yourgraphs data. and tables, You canshare charts, ormake aposter. board, display theresults onabulletin can give presentation, anoral You your class. obtain from your investigations to membersof findings. publishtheirmostimportant Scientists usually andtheconclusions drew. they obtained, thedatathey run, thatshow reports how write were theirexperiments They orthepublic. government agencies, otherscientists, with share might They usuallyshare They theirresults. there. mostscientistsdonotstop However, aninvestigation. of What are variables? What are ahypothesis? How doyouform Experimental Research communicated? results How are rwt ifrn mut fantibiotics. different amountsof or with time, fordifferent lengthsof at two different temperatures, c thatstay Thevariables thesameare called antibiotic. is thesameexcept of variable sure thatevery forthetype bacteria. of growth isthe thedependent variable In thisexperiment, variable. to changes theindependent madeonpurpose result of independent variable. antibioticappliedto isthe thebacteria of Thetype bacteria. two different of antibioticsonthegrowth testing theeffectof Suppose is anexperiment scientist changes onpurpose. andany observations. previous information, new knowledge, prior your you use To ahypothesis, form orevent thatcanbetestedfor anobservation scientifically. o In a planned experiment, factors called variables are factors calledvariables In aplannedexperiment, A Another way to solve scientificproblems isthrough You alsohave thechance to communicate thedatayou Analyzing conclusions dataand drawing make uptheend o ts hc niitcwrsbs,you have to make To test which antibiotic works best, A nstants d h e y p p e othesis nd o xml,you theexperiments should notrun For example, . e nt v (hi PAH thuh sus)isapossibleexplanation ar iab ind le e p is thefactor thatmay change asa e nd e nt v ar i ab le is afactor thatthe SC.H.1.3.5 ✔ FC A 6. T

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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2. 1. descriptive research: dependent variable: control: constant: Mini Glossary in a summary paragraph. asummary in theindependentvar dependent variable, Identify the Identify theconstants. how you setuptheexperiment. will Decide thatyouImagine wantto findoutwhetherplantsgrow better inred orbluelight. compares descriptive research research andexperimental design. Write asentence that Review the terms andtheirdefinitionsintheMini Glossary. After You Read variable of changesmadeonpurposetotheindependent scientific questionsthroughobservation applied toit groups exceptthattheindependentvariableisnot a samplethatistreatedliketheotherexperimental variable thatstaysthesameinanexperiment a factorthatmaychangeasresult type ofresearchdesignthatanswers and projectstohelpyoulearnmore aboutdoingscientificresearch. Visit fl7.msscience.com to accessyourtextbook,interactive games, al,adtecnrl Present theinformation andthecontrol. iable, scientific method: model: independent variable: hypothesis (hiPAHthuhsus): experimental research: purpose too quickly,orarebigsmalltoobservedirectly use ofaseriescarefullycontrolledsteps scientific questionsbytestingahypothesisthroughthe an observationoreventthatcanbetestedscientifically a representationofthingsthathappentooslowly, steps tofollowtrysolveproblems a factorthatscientistchangeson type ofresearchusedtoanswer a possibleexplanationfor Reading Essentials Section End of 13 discoveries ontherightside. results ofthoseadvancesor discoveries ontheleftsideand advances intechnologyor chart asshownbelow.List ● Create anOutline headings andsupportingdetails. outline thatincludesthemain separate sheetofpaper,writean D section 14 ■ ■ What You’llLearn chapter Identify Study Coach worldwide be communicated scientific discoveriesto technology allows how modern your life technology influence how scienceand 3 motivations; Benchmarks—SC.H.1.3.6: Also covers: knowledge andtechnology…caneventuallybecomeavailabletoeveryone. 1 The NatureofScience andTechnology

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and Technology The NatureofScience Results Science, Technology,andEngineering The studentknowsthattechnologicaldesignshouldrequiretakingintoaccountconstraints…; On a The studentrecognizesthescientificcontributionsthataremadebyindividualsofdiversebackgrounds,interests,talents,and h opc ici rdc ftechnology. The compact disc isaproduct of compact disc is anobjectthatusedto store information. The One objectthatyou useisthecompact might disc. day. or asocial-technical system. production, Technology alsocanbeanewsystem of doing something. oranewmethodtechnique for such asamicroscope, tool The canbeaconventional tool, pH paper. or apiece of Theproduct canbeanobject such asacalculator, systems. doctors operate onbabiesto save theirlives. Miniature help instruments medicineinto the body. dose of becontrolledmight by askinpatch thatreleases aconstant that affectyour lifestyle. such asDVDs, new discoveries have ledto newproducts, When istechnology aproduct? The ConceptofTechnology Scientific Discoveries Name three scientific discoveries day. thataffectyour lifeevery Technology canbeaproduct orobjectthatyou useevery and tools, products, Technology of includesavariety Adisease Technology helpsmany peoplelive healthierlives. For example, Science influences your lifeinmany ways. Read toLearn YouBefore Read SC.H.3.3.6: The studentknowsthat…

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. When is technology a method or technique? At one time, doctors had to do surgery to see inside the human body. X rays were the first technology that allowed doctors to find some medical problems without surgery. Today, doctors use many other methods and techniques to identify medical problems. All of these methods and techniques are technology because they represent a new way of doing things. When is technology a system of production? An assembly line is a system of production. Before assembly lines, one person usually created a product from start to finish. Several workers make a product on an assembly line. Each worker does only one part of the process. Products are made faster and cheaper using assembly lines. The assembly line system is an example of technology. When is technology a social-technical 1. Determine How is an assembly line an example system? of technology? A hospital is another example of technology. Physicians, technicians, and nurses use many tools to find and treat medical conditions. The collection of people, tools, methods, and systems are a form of technology. Biotechnology and the Human Body Technology is used to solve problems in the human body too. When technology is applied to living organisms, it is referred to as biotechnology. An example of using biotechnology in the human body is the hormone insulin. Insulin is a hormone produced in the pancreas. It controls the amount of sugar in the blood. A person with a particular type of diabetes produces too little or no insulin. In the past, animal insulin was used to treat diabetic patients. Animal insulin is not exactly the same as human insulin. Physicians were not certain about the future effects of using animal insulin in humans. Animals also might not be able to 2. Infer Why do you think provide enough insulin to meet the growing need for it. physicians were worried Scientists and engineers worked to find a solution. In about the long-term effects of animal insulin on 1982, the Federal Drug Administration approved the use of humans?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright genetically engineered human insulin. The hormone was produced in the laboratory using biotechnology. It was the ﬁrst drug approved that was manufactured using biotechnology. Engineers planned the equipment and manufacturing processes needed to make human insulin in large amounts.

Reading Essentials 15 What is engineering? Scientists and engineers often work together to find a technological solution. An engineer takes scientific information or a new idea and finds a way to use the information to solve a problem or to mass-produce a product. For example, scientists developed the genetically engineered 3. Identify What is one human insulin. They made small amounts using common problem that engineers laboratory equipment such as test tubes, beakers, and flasks. helped solve? After human insulin was approved for use, companies needed to find ways to make large quantities available to diabetic patients. Engineers designed the equipment and processes needed to make large quantities of the insulin. Engineers work in many areas of science. Types of engineers include aeronautical, aerospace, biomedical, chemical, electrical, and mechanical. Think of the products you use everyday. Engineers have a major role in the manufacturing of these products. Finding Scientific Solutions Scientists and engineers use a process to find scientific solutions to problems. They begin by clearly defining the problem or need. Scientists could say that they want to produce a new drug to help people live healthier lives. This goal is too broad. They need to make the definition of the problem or need more specific. For example, a group of scientists may say that they want to find a way to produce insulin that is the same as the insulin produced naturally in the human body. This clear statement helps the team of scientists focus their efforts on the same problem or need. Likewise, engineers would state their problem or need clearly. Their goal might be to produce enough of the drug to meet the needs of all diabetic patients in the United States. How do scientists and engineers evaluate possible solutions? Once the problem or need is clearly defined, scientists and engineers begin searching for possible solutions. A problem 4. Explain How is the best solution found? might have more than one solution. Scientists and engineers work to find the best solution. They evaluate the advantages Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright and disadvantages of each possible solution. They also determine if each possible solution follows scientific principles. The best solution is likely to be the one with the fewest risks and the most benefits.

16 The Nature of Science and Technology Continued Evaluation After a solution in found, scientists develop the product, such as insulin, in small quantities. They also begin to test the procedures and processes needed to produce more of the product. Then, scientists and engineers works together to design the equipment, procedures, and processes needed to make the product in large quantities. Business professionals and environmental professionals also evaluate each proposed solution. Business professionals provide information about the cost of the proposed solution. For example, if human insulin is too expensive, diabetic 5. List four professionals who evaluate solutions. people may not be able to afford to buy it. Environmental professionals study the effect of each proposed solution on the environment. They make certain that the environment is not harmed when a product is produced. How do scientists and engineers test the solution? Once everyone agrees on the best solution, a model is built. The model is tested before manufacturing begins. Testing the model helps the team find design flaws. During testing, the team will identify constraints in the design. A constraint is a limiting factor in the design such as maximum speed of the production line, or minimum temperature for operation. After the model passes all of the design tests, a pilot plant will be built. A pilot plant is a smaller version of the real production equipment that uses actual manufacturing conditions. Testing continues in the pilot plant to make sure the manufacturing process works well. Mistakes and problems can be fixed before a large plant is built. Finally, the large manufacturing plant is built and the manufacturing process 6. Discuss how a pilot plant begins. Large quantities of the product can now be made. saves money. There are many steps in the technological solution process. Testing and evaluation are done at every step. Scientists and engineers want to find any mistakes in the process as early as possible. The earlier a mistake is found, the less expensive it is to fix. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 17 After You Read Mini Glossary biotechnology: technology applied to living organisms pilot plant: a smaller version of real production equipment constraint: a limiting factor in a design that closely models actual manufacturing conditions engineer: a person who takes scientiﬁc information or a new idea and ﬁnds a way to use the information to solve a problem or to mass-produce a product

1. Review the term and its deﬁnition in the Mini Glossary. Write a sentence explaining the purpose of a pilot plant.

2. Choose one of the question headings in the Read to Learn section. Write the question in the space below. Then write your answer to that question on the lines that follow.

Write your question here.

3. Describe a problem in the world today that science could help solve. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about science, engineering, and technology. 18 The Nature of Science and Technology chapter Properties and Changes of Matter 23 section ●1 Physical and Chemical Properties Benchmarks—SC.A.1.3.1 Annually Assessed: The student identiﬁes various ways in which substances differ; SC.A.1.3.5: The student knows the difference between a physical change in a substance and a chemical change. Also covers: SC.A.1.3.2; SC.A.1.3.4; SC.A.1.3.6; SC.H.1.3.4; SC.H.1.3.7; SC.H.2.3.1

Before You Read What You’ll Learn ■ about physical and How would you describe what someone looks like to a friend? chemical properties of matter ■ how to describe objects based on physical properties

Read to Learn Study Coach Create a Quiz As you read, Physical Properties write quiz questions about the Imagine you are visiting the Florida State Fair. You spot main ideas and vocabulary the most amazing ride you have ever seen. How will you terms. When you finish reading, answer your quiz questions. If describe this ride to your friends? What features will you use you miss any answers, find the in your description? Maybe you will tell them it is large, correct answer in the section. blue, and made of wood. These features are all physical properties, or characteristics, of the ride. A physical property is a characteristic that you can observe without changing or trying to change the substance. How an object looks, smells, sounds, or tastes are examples of physical properties. You can describe matter by its physical properties. How can your senses help describe matter? Some physical properties describe what matter looks like. You can use your senses of sight, smell, or taste to describe matter. For example, you can see the color and shape of an object. You also can touch objects and describe what they ●A Classify Make the feel like. You can smell odors and taste flavors of some following folded table to help objects. (You should never taste anything in the laboratory.) you list the physical and chemical properties of different How can matter be described by state? kinds of matter. When you describe matter, you need to describe its state, or Physical Chemical form. Is it a solid, a liquid, or a gas? This property is known Matter Properties Properties Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright as state of matter. Your chair, book, and pen are examples of matter in the solid state. Milk, gasoline, and vegetable oil are examples of matter in the liquid state. Helium in a balloon or the air you breathe are matter in the gas state.

Reading Essentials 19 Can matter exist in all three states? Water is one substance that you’ve probably seen or felt in all three states. You drink or swim in liquid water. You might put solid water, or ice, in your soft drink. You might even skate on solid water in the winter. Water in the gas state is in the air you breathe. What properties depend on size? Some physical properties, such as volume and mass, depend on the size of the object. Volume Suppose you need to know the volume, or the amount of space inside a box. To ﬁnd the volume, you multiply its width, height, and depth measurements. Volume is a physical property that depends on size. Mass and Weight Mass is another physical property that depends on size. Mass is the amount of matter in an object. 1. Identify Name two A bowling ball has more mass than a basketball. Weight properties that depend depends on the mass of the object, but it also depends on on size. gravity. On other planets your weight would change, but not your size or your mass. What properties do not depend on size? Some physical properties of materials do not depend on size. Properties like color, density, and solubility do not change whether the amount of material is great or small. Density Density is the amount of mass in a given volume. To ﬁnd the density of an object, divide the object’s mass by its volume. Water in a drinking glass has the same density as water in a bathtub. The density of an object will change, however, if the mass changes and the volume remains the same. Solubility Another property that does not depend on size is solubility (sahl yuh BIH luh tee). Solubility is the number of grams (g) of one substance that will dissolve in 100 g of 2. Explain The boiling another substance at a given temperature. For example, the point of water in a tea kettle is the same as the boiling number of grams of sugar that dissolves in 100 g of water does point in a 20-qt soup pot. not change if the water is in a large pitcher or poured into a Why? drinking glass. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Melting and Boiling Point Melting and boiling point also do not depend on size. Melting point is the temperature at which a solid changes into a liquid. Boiling point is the temperature at which a liquid changes into a gas.

20 Properties and Changes of Matter The ﬁgure below shows the melting and boiling points of several substances along with other physical properties. Picture This Physical Properties of Several Substances 3. List the different physical Melting Solubility in properties shown in the Density Boiling Substance State point cold water table. (g/cm3) point (C) (C) (g/100 mL)

Ammonia gas 0.7710 -78 -33 89.9

Bromine liquid 3.12 -7 59 4.17

Calcium carbonate solid 2.71 1,339 898 0.0014

Iodine solid 4.93 113.5 184 0.029

Potassium hydroxide solid 2.044 360 1,322 107

Sodium chloride solid 2.17 801 1,413 35.7

Water liquid 1 0 100 —

Magnetic properties Some matter can be described by the way it behaves. For example, some materials pull iron toward them. These are called magnetic. Lodestone is a rock that is magnetic. Other materials can be made into magnets like the magnets on your refrigerator. The ﬁgure below shows which properties depend on size and which do not. Picture This Physical Properties of Matter 4. Compare and Contrast Do more Depend volume, mass, weight physical properties on size depend on size or not depend on size? Do not density, melting/boiling point, solubility, depend on size ability to attract a magnet, state of matter, color

Chemical Properties A chemical property is a characteristic that cannot be observed without changing the substance. Imagine that you Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright didn’t know what a match was. Could you tell just by looking at it that it would burn? The ability to burn is a chemical property. After a match burns, the match is permanently changed.

Reading Essentials 21 After You Read Mini Glossary chemical property: characteristic that cannot be observed physical property: characteristic that can be observed without changing a substance without changing or trying to change the substance

1. Review the terms and their deﬁnitions in the Mini Glossary. Explain in your own words the difference between chemical properties and physical properties.

2. Fill in the Venn diagram below to compare and contrast physical and chemical properties. Include examples of each type of property.

Ways to Describe Objects

Physical Chemical Properties Properties Deﬁnition Deﬁnition

Examples Example

3. At the beginning of the section, you were asked to make a quiz about the main ideas and vocabulary terms. How did you decide what the main ideas were? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about physical and chemical properties. 22 Properties and Changes of Matter chapter Properties and Changes of Matter 23 section ●2 Physical and Chemical Changes Benchmarks—SC.A.1.3.1: The student knows the difference between a physical change in a substance and a chemical change. Also covers: SC.H.1.3.1; SC.H.1.3.3; SC.H.1.3.4; SC.H.1.3.5; SC.H.1.3.7; SC.H.3.3.5

Before You Read What You’ll Learn ■ to compare physical A log is cut into boards. Then, the boards are used to make and chemical changes a table. What properties of the log have changed? What has ■ examples of physical stayed the same? and chemical changes

Read to Learn Underline Main Ideas Physical Changes Underline the main ideas of physical and chemical changes What happens when an artist changes a lump of clay into as you read about them. Then a pot? Does what is in the clay change? No, what is in the highlight an example of each clay does not change. Only the way the clay looks changes. kind of physical and chemical The shape of the clay changes from a lump of clay to a pot. change. This kind of change is a physical change. A physical change is a change in the way an object looks, but not in what the object is made of. For example, a frozen pond in winter looks totally different than the pond in the summer. The water changes state from a solid in the winter to a liquid in the summer because of a change in temperature. Although the physical properties of solid ice are different from the physical ●B Compare and Contrast properties of liquid water, the chemical makeup, or Make the following Foldable to composition, is the same. The water molecules are still show how physical changes and made up of the same elements—hydrogen and oxygen. chemical changes are similar and different. How is changing shape a physical change? Chemical Physical Changes Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Have you ever crumpled a piece of paper into a ball? If Changes so, you caused a physical change. The crumpled ball is still the same piece of paper. When you cut a banana, the fruit is still a banana. You change only its form. When you cut, tear, grind, or bend matter, you cause a physical change.

Reading Essentials 23 How is dissolving a physical change? What happens when you add sugar to iced tea? Does the sugar disappear? It may seem to disappear. But, if you taste the tea, it is sweet. The sugar dissolves in the tea. The particles of sugar spread out in the tea. The form of the sugar changes, but the make-up of the sugar stays the same. So, dissolving is a physical change. How is changing state a physical change? Matter can change from one state to another. Liquid water that freezes into ice is still water. Both liquid water and solid ice are made up of the same type of molecules. So, changes in state are physical changes. A liquid also can change into a gas. Vaporization (vay pruh ZAY shun) is a change from a liquid to a gas. 1. Infer When you take a hot shower, water droplets may Water vaporizes when it boils and turns into steam. appear on the bathroom Condensation (kahn den SAY shun) occurs when a gas mirror. What is this an changes into a liquid. What happens to a glass of ice water example of? if it sits at room temperature? Water forms on the outside of the glass. This is an example of condensation. Sublimation (sub luh MAY shun) is a process in which a solid changes directly to a gas without becoming a liquid first. When dry ice melts, it turns into carbon dioxide gas. You may have seen smoke made from dry ice while watching a play. Deposition (de puh ZIH shun) is a process in which a gas changes directly to a solid without becoming a liquid first. Frost that forms on the ground on a cold, humid night is an example of deposition. The figure below shows these changes in state.

Picture This Sublimation 2. Explain Look at the ﬁgure. Tell what two Melting Vaporization processes happen when a Solid Freezing Condensation solid changes ﬁrst to a Liquid liquid and then to a gas. Gas Deposition

Chemical Changes

Do you enjoy ﬁreworks? The explosions and colors are Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright examples of chemical changes. In a chemical change, substances are changed into different substances. This means the makeup of the substance changes. When ﬁreworks explode, compounds change into different compounds.

24 Properties and Changes of Matter How is rusting a chemical change? Have you ever seen a bike that was left out in the rain? What happened to the bike? You may have noticed that the steel parts of the bike, such as the frame and the chain, can rust after awhile. This happens when oxygen and water in the air react with the iron in steel. The iron and oxygen atoms combine to form a reddish, powdery substance called rust. So, rusting is an example of a chemical change. Signs of Chemical Changes Physical changes are usually easy to spot. You can see when something changes shape or state. But, how do you know when chemical changes happen? You have probably seen chemical changes before—you just did not know it. Have you seen the leaves on trees change color in the fall? If so, you have seen a chemical change. The change in the color of the leaves is not caused by a green pigment changing into a red pigment. A pigment is a chemical that makes things certain colors. Paints have pigments in them. In summer, trees make a green pigment called chlorophyll (KLOHR uh ﬁhl). This makes the leaves green. In fall, trees stop making chlorophyll. The chlorophyll already in the leaves changes into colorless chemicals. Then you see the 3. Explain What is the green pigment in leaves? yellow, red, and orange pigments that have been in the leaves all along. How is color a sign of a chemical change? Have you ever seen an apple slice turn brown? A chemical change occurs when an apple reacts with oxygen in the air. The chemical change makes the apple turn brown. Heat also causes chemical changes in food. Bread turns brown as it cooks because a chemical change occurs. How is energy a sign of chemical change? Many substances must absorb energy to have a chemical change. For example, what do you add to pancake batter to make it turn into a pancake? Energy. The energy absorbed 4. Apply Name another by the runny pancake batter as it cooks causes a chemical example of how color is a change. A solid pancake is the result. Many chemical sign of chemical change in food.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright changes require heat. A release of energy is another sign of a chemical change. Fireworks release energy in the form of light when they undergo a chemical change. Burning is a chemical change that releases energy in the form of heat and light.

Reading Essentials 25 How is odor a sign of chemical change? Have you ever opened a container that has been in the

F T OC refrigerator too long? Did the food inside smell bad? The A U C Annually Assessed

S F Benchmark Check bad smell is a sign that the food has spoiled. When foods spoil, they undergo a chemical change. The change in odor SC.A.1.3.1 is a sign of chemical change. This sign can save lives. A bad ✔ 5. Explain Why odor is a sign that you should not eat the food. should foods whose odors have changed be How is the formation of gases or solids a sign avoided? of chemical change? You can see bubbles if you pour vinegar on baking soda. The bubbles in the vinegar are a gas. The gas formed in a chemical reaction. Gas formation is a sign of chemical change. Sometimes, when you mix two liquids, a solid forms. This solid is called a precipitate (prih SIH puh tut). When a precipitate forms, it is a sign of a chemical change. Can physical and chemical changes be reversed? Ice can melt and become water, then freeze again to become ice. Melting and freezing are physical changes. Substances produced by chemical changes cannot be changed back to their original substances. When a log burns, the gases and ash that form cannot be changed back into a log. Pancakes cannot be turned back into batter. Physical Versus Chemical Change Here are the important things to remember about physical and chemical changes. In a physical change, the makeup of the substance does not change. However, the substance does change form. In a chemical change, the makeup of the substance changes and the substance changes form. Picture This The table below shows some examples of physical and 6. Use Scientiﬁc chemical changes. Explanations Give another example of a substance undergoing a Examples of Physical and Chemical Changes physical change and a Substance Physical Change Chemical Change chemical change. Apple Being cut into pieces Cut surfaces turning brown Egg Mixing together egg white and yolk Spoiling and giving off an odor Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Copper Being pounded and bent Green patina forming Wood Being cut into lumber Burning Water Boiling Mixing with an antacid tablet Marble Carving into a statue Dissolving in acid rain

26 Properties and Changes of Matter Physical Changes When a substance such as copper or wood undergoes a physical change, the original substance still remains after the change. To make the Statue of Liberty, copper sheets were bent and pounded into shape. Trees are cut into lumber. After these physical changes, the copper and the wood are still the same substances. Chemical Changes When a substance undergoes a chemical change, the original substance no longer is present after the change. New substances are made during a chemical change. The Statue of Liberty was bright and shiny when it was new. Over time, the copper reacted with air to form a green 7. Explain What substance coating called patina. When wood is burned, it is changed reacts with copper to form patina? into gases and ash. During these chemical changes, the copper and the wood changed into new substances. How are physical and chemical changes used in recycling? Recycling is a way to separate used items into their different parts. Then you can reuse the parts. Recycling involves physical and sometimes chemical changes. Rubber tires can be shredded and added to asphalt pavement and playground surfaces. Glass bottles can be smashed and used in asphalt pavement, new containers, and even artwork. Some plastics can be melted and formed into new products. Recycling objects helps keep our landﬁlls from getting too full. Conservation of Mass In a chemical change, the makeup, or the composition, of the matter changes. Particles in the matter rearrange and new substances are created. When wood burns, the particles in the matter rearrange and turn into gases and ash. The particles are not created or destroyed. The law of conservation of mass states that the total mass of matter is the same before and after physical or chemical Applying Math changes. Matter cannot be created or destroyed. Scientist Antoine Lavoisier (AN twan • luh VWAH see ay) 8. Apply A log with a mass of 2 kg is burned. What is proved the law of conservation of mass in the 1700s. This the mass of the gases and law can sometimes be difﬁcult to understand. When a ash that are produced when

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright candle burns, some of it seems to disappear. Lavoisier realized the log burns? that the mass of a candle doesn’t disappear. The mass changes form into the gases given off when the candle burns.

Reading Essentials 27 After You Read Mini Glossary chemical change: a change that happens when substances physical change: a change in the way an object looks, but are changed into different substances not in what the object is made of condensation: a change from a gas into a liquid sublimation: a change directly from a solid to a gas without deposition: a change directly from a gas to a solid without becoming a liquid ﬁrst becoming a liquid ﬁrst vaporization: a change from a liquid to a gas law of conservation of mass: the total mass of matter is the same before and after physical or chemical changes

1. Review the terms and their deﬁnitions in the Mini Glossary. On a sunny winter day, ice and snow sometimes seems to disappear. What term describes this change in state? Explain the term in a sentence.

2. Write physical change or chemical change in the blank after each example to tell what kind of change each example is. a. Spoiled food ______b. Sublimation ______c. Making wood into furniture ______d. Fireworks exploding ______e. Nails rusting ______f. Bending metal sheets ______

3. You were asked to underline ideas about physical and chemical changes and then highlight an example of each kind of change. Did this strategy help you learn about physical and chemical changes? Why or why not? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about physical and chemical changes. 28 Properties and Changes of Matter chapter Inside the Atom 33 section ●1 Models of the Atom Benchmarks—SC.A.2.3.2: The student knows the general properties of the atom and accepts that single atoms are not visible. Also covers: SC.H.1.3.1; SC.H.1.3.2; SC.H.1.3.3; SC.H.1.3.6; SC.H.1.3.7; SC.H.3.3.5

Before You Read What You’ll Learn ■ how scientists What is the smallest thing you have ever seen? Was this discovered subatomic thing made up of smaller parts? Name them. particles ■ how the atom model was developed ■ the structure of the atom ■ that all matter is made up of atoms

Read to Learn Study Coach Outline Make an outline of First Thoughts the section as you read. Be sure to include vocabulary words Do you like mysteries? Are you curious? All through history, and main ideas. Review your humans have wondered about things that can’t be seen. One outline when you ﬁnish reading of the things humans have wondered about is what matter is the section. made of. Some early thinkers thought that matter was made of tiny particles. They thought that you could cut matter in half and then in half again many times. Finally, you would have a piece so small that you could not cut it any more. You would have only one particle left. This particle is too small to be seen by human eyes. Early thinkers named this smallest particle the atom. The word atom means “cannot be divided.” How do you describe something that you can’t see? Thousands of years ago, people could not prove that atoms existed. In early times, scientists did not do experiments. They discussed their ideas until they agreed on them. Today, scientists will not accept a theory that is not supported by 1. Explain Why didn’t early experimental evidence. Even if early scientists wanted to scientists do experiments?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright experiment to ﬁnd out about atoms, they could not have. Long ago, people didn’t know much about what we call chemistry, or the study of matter. Equipment that scientists use today to study matter had not yet been invented. Atoms were still a mystery as recently as 500 years ago.

Reading Essentials 29 A Model of the Atom ●A Compare and Contrast For a long time, no one had new ideas about the atom. Make the following Foldable to Finally in the 1700s, scientists started thinking about atoms help you compare and contrast again. Chemists were learning about matter and how it different models of the atom by changes. They put substances together to form new Dalton, Thomson, and substances. They also took substances apart to ﬁnd out what Rutherford. they were made of. Scientists found that some substances could not be broken down into simpler substances. They John Dalton called these substances elements. An element is matter made up of only one type of atom. For example, iron is an J. J. Thomson element made of only iron atoms. Silver is an element made of only silver atoms. Rutherford What was Dalton’s concept of the atom? John Dalton was an English schoolteacher in the early 1800s. He had these ideas about matter: (1) Matter is made up of atoms. (2) Atoms cannot be divided into smaller pieces. (3) All atoms of an element are exactly alike. (4) Different elements are made of different kinds of atoms. Dalton thought of an atom as a hard sphere, or ball, like a tiny marble. How was Dalton’s theory tested? In 1870, an English scientist named William Crookes experimented with a glass tube as shown in the ﬁgure. The tube had almost all the air removed from it. The tube had two pieces of metal called electrodes inside. The electrodes were connected to a battery by wires.

Cathode Shadow Picture This rays 2. Identify Draw a circle around the positive () end Anode of the tube. Then, draw a Object in the square around the negative Cathode () end. path of the particles What was in Crookes’s tube? An electrode is a piece of metal that conducts electricity. An anode is an electrode with a positive charge. The anode is connected to the positive side of the battery. The cathode

is an electrode with a negative charge. The cathode is Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright connected to the negative side of the battery. Crookes’s tube is shown in the ﬁgure above. In this tube, the cathode was a small metal disk. The anode was a larger metal disk. In the middle of the tube was an object shaped like a cross.

30 Inside the Atom What happened in Crookes’s tube? When Crookes connected the battery, the tube lit up with a green glow. A shadow of the cross appeared on the anode. Crookes believed that something was ﬂowing from the cathode to the anode. The cross was blocking the ﬂow, causing a shadow. Crookes thought that the glow was caused by rays, or streams of particles. He called the rays cathode rays because they came from the cathode. Crookes’s tube is called a cathode-ray tube, or CRT. Many televisions and computer monitors have a type of CRT. Discovering Charged Particles Some scientists were not sure that cathode rays were streams of particles. They thought the rays were just a form of light. In 1897, an English scientist named J. J. Thomson did an experiment with cathode rays. He placed a magnet beside a CRT. The magnet caused the cathode rays to bend. Light cannot be bent by a magnet. So, the beam could not be light. Thomson concluded that the rays were made of charged particles of matter that came from the cathode. What are electrons? 3. Explain Why couldn’t the cathode rays be light? Thomson did many more experiments with CRTs. He made cathodes of different metals. He also used different gases in the tube. Each time, the same charged particles were produced. Thomson decided that cathode rays were negatively charged particles of matter. He knew that opposite charges attract each other. He decided the particles in the CRT were negatively charged because they were attracted by the positively charged anode. These particles are now called electrons. Electrons are negatively charged particles. Thomson thought that electrons were part of every kind of atom because every kind of cathode material produced electrons in his experiment. Thomson’s results showed that particles smaller than atoms do exist. What did Thomson’s discovery mean? 4. Describe Why did Thomson think all atoms Thomson’s discovery meant that atoms must have negatively contained electrons?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright charged particles inside of them. If that is so, why isn’t all matter negatively charged? Thomson believed that atoms also must have some positive charge. That way, the negative and positive charges would neutralize each other, or cancel each other out.

Reading Essentials 31 How did Thomson model the atom? Thomson made a new model of the atom based on his 5. Compare and Contrast How was findings. Dalton thought of an atom as a solid ball that was Dalton’s model of the atom the same throughout. Thomson pictured a sphere of positive different from Thomson’s charge. Negatively charged electrons were placed evenly in model? the sphere. The positive charge of the sphere is equal to the negative charge of the electrons. Therefore, the atom is neutral. Later, scientists discovered that not all atoms are neutral because the number of electrons in each atom can change. Rutherford’s Experiments A model is not accepted by scientists until it has been tested. In 1906, Ernest Rutherford and his coworkers began an experiment to find out if Thomson’s model of the atom was correct. They fired positively charged bits of matter, called alpha particles, at a thin film of metal. Since alpha particles are positively charged, they would be repelled by matter that is positively charged. The figure at the top of the next page shows how the 6. Infer Why would alpha experiment was set up. Alpha particles were fired at a sheet particles be repelled by of gold foil. The foil was only 400 nanometers thick. There matter that is positively charged? was a fluorescent (floo REH sunt) screen around the foil. The screen gave a flash of light each time it was hit by a charged particle. What did Rutherford think would happen? Rutherford predicted that most of the particles would pass straight through the gold and hit the screen on the other side. He didn’t think that the gold foil contained enough matter to stop the speeding alpha particles. He thought that the positive charge in the gold atoms might cause a few minor changes in the path of the alpha particles, but not very often. Rutherford’s hypothesis made sense. Remember that, in Thomson’s model, the positive charge is neutralized by nearby electrons. Was Thomson’s model wrong? The figure at the top of the next page also shows the results of Rutherford’s experiments. Rutherford was surprised to find that some of the alpha particles bounced backward off the

foil. How could he explain this event? He decided that the Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright positively charged alpha particles were moving so quickly that it would take a large positive charge to make them bounce back. This meant that Thomson’s model of the atom with an equal mix of positive and negative charge was incorrect.

32 Inside the Atom A few of the particles bounce Most of the particles Picture This il. 7. Determine Does the ﬁgure show all particles passing through the gold Sour foil? char

A Model with a Nucleus Rutherford proposed a new model of the atom, shown in the ﬁgure below. The nucleus is a tiny space in the center of an atom that has a postive charge and contains almost all of the atom’s mass. In 1920, Rutherford’s ideas about the nucleus were proven true when scientists identiﬁed protons. A proton is a positively charged particle that is in the nucleus of all atoms. The almost-massless electrons move in the empty space around the nucleus.

Nucleus Picture This 8. Identify What are the particles ﬂoating around the nucleus of the atom?

What did Rutherford’s model explain? Rutherford’s new model explained what happened in his experiment. Most alpha particles move through the foil with

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright little or no interference because atoms are made up of mostly empty space. But, if an alpha particle hit the nucleus of a gold atom, the strong positive charge in the nucleus repelled the alpha particle. The alpha particle then bounced backward.

Reading Essentials 33 What did Rutherford’s model not explain? Rutherford’s model explained why some alpha particles bounced back. However, his model did not answer all questions about the atom. For instance, an atom’s electrons have almost no mass. In Rutherford’s model, the only other particle in the atom was the proton. So, the mass of an atom should be about equal to the mass of its protons. However, the mass of most atoms is at least twice as great as the mass of its protons. Rutherford’s model did not explain this. Where does the extra mass come from? To explain the extra mass in an atom, scientists thought there must be another particle in the nucleus. This particle was called the neutron (NEW trahn). A neutron is a particle that has the same mass as a proton but has no electrical charge, or is neutral. It was hard to prove that neutrons exist. Because neutrons have no charge, they are not attracted by magnets and they do not make ﬂuorescent screens light up. It took 20 more years before more modern experiments were able to show that atoms contain neutrons. Picture This Nuclear Atom Model 9. Identify How many protons are in this atom? How many electrons are there?

When neutrons were discovered, the model of the atom changed again. The nuclear atom, shown in the ﬁgure above, has a tiny nucleus tightly packed with positively charged protons and neutral neutrons. Negatively charged electrons are found in the empty space around the nucleus. T FO A C U The number of electrons in a neutral atom equals the C Annually Assessed

S F Benchmark Check number of protons in the atom. SC.A.2.3.2 How big are atoms?

✔ 10. Explain What Drawings of the nuclear atom like the one above don’t Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright makes up most of an show how small the nucleus is compared to the rest of the atom? atom. Imagine that the nucleus of an atom is the size of a table-tennis ball. The atom would have a diameter greater than 2.4 km. Most of an atom is empty space.

34 Inside the Atom Further Developments Scientists ﬁrst thought electrons orbit, or travel around, the ●B Draw and Describe nucleus of an atom like the planets travel around the Sun. On a sheet of notebook paper, They thought that the negatively charged electrons were draw the current model of the attracted to the positive charges in the nucleus like the Moon atom and describe it. is attracted to Earth. But scientists later learned that electrons are in constant, unpredictable motion. The motion of electrons cannot be easily described by an orbit. It is impossible to know exactly where an electron is at any particular moment. These ﬁndings led to even more experiments about atoms. Can the behavior of electrons be explained? Scientists continued to struggle with how to explain the unpredictable nature of electrons. New theories and models were needed. One way to explain the movement of electrons is to think of them as waves, not particles. Thinking of electrons in this way helped scientists come up with the current model of the atom. What is the electron cloud model? The latest model of the atom is the electron cloud model, shown below. The electron cloud is the area around the nucleus of an atom where electrons travel. The electrons are more likely to be close to the nucleus than far away. That is because the negative electrons are attracted to the positive charge of the protons in the nucleus. Notice that the cloud in the model has a fuzzy outline. There is no clear boundary because electrons could be anywhere within the cloud.

Electron Cloud Model Nucleus Picture This 11. Draw and Label Shade the area of the electron cloud were the electrons are most likely to be.

This may be the latest model of the atom, but it could

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright certainly change. Scientists may ﬁnd out new things about the atom. They may even decide that this model is incorrect. Science is always changing as long as scientists ask questions and do more experiments.

Reading Essentials 35 After You Read Mini Glossary anode: an electrode with a positive charge nucleus: a tiny space in the center of an atom that has a cathode: an electrode with a negative charge postive charge and contains almost all of the atom’s electron: a negatively charged particle mass electron cloud: the area around the nucleus of an atom neutron (NEW trahn): a particle that has the same mass as where electrons travel a proton, but has no electrical charge element: matter made up of only one type of atom proton: the positively charged particle that is in the nucleus of every atom 1. Review the terms and their deﬁnitions in the Mini Glossary. What do you know about the atoms of the element gold? Answer in a complete sentence.

2. Look at the ﬁgure below. Label the parts of the current model of an atom. Explain what each part is.

+ +

3. At the beginning of the section, you were asked to make an outline as you read. How did outlining help you learn about atoms? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about models of the atom. 36 Inside the Atom chapter Inside the Atom 33 section ●2 The Nucleus Benchmarks—SC.A.2.3.2: The student knows the general properties of the atom and accepts that single atoms are not visible. Also covers: SC.H.1.3.1; SC.H.1.3.2; SC.H.1.3.3; SC.H.1.3.4; SC.H.1.3.5; SC.H.1.3.6; SC.H.3.3.1; SC.H.3.3.4; SC.H.3.3.5; SC.H.3.3.6; SC.H.3.3.7

Before You Read What You’ll Learn ■ about radioactive decay Every person is different. What are some things that make ■ what half-life means one person look different from another person? ■ how radioactive isotopes are used

Read to Learn Highlight Main Ideas As Identifying Numbers you read, highlight the main ideas under each heading. After The electron cloud model is an example of what an average you ﬁnish reading, review the nuclear atom looks like. But what makes atoms of different main ideas of the lesson. elements different? The atoms of different elements have different numbers of protons. The atomic number of an element is the number of protons in the nucleus of an atom of that element. The element hydrogen has the smallest atomic number. It has only one proton in its nucleus, so hydrogen’s atomic number is 1. The element uranium has the greatest atomic number of a naturally occurring element. It has 92 protons in its nucleus. Its atomic number is 92. How many neutrons are in the nucleus? A certain type of atom can have different numbers of neutrons in its nucleus. For example, most carbon atoms ●C Build Vocabulary have six protons and six neutrons. But, some have seven or Make the following Foldable and eight neutrons. All of these atoms are carbon atoms because write the deﬁnitions of each of they all have six protons. the terms from this lesson. These carbon atoms with different numbers of neutrons are called isotopes (I suh tohps). Isotopes are atoms of Atomic Number Isotopes Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright the same element that have different numbers of neutrons. Mass Number Radioactive Carbon-12 is an isotope that has six protons and six neutrons. Decay Carbon-13 has six protons and seven neutrons. Carbon-14 Transmutation Alpha Particle

has six protons and eight neutrons. Together, the protons Beta Particle and neutrons make up most of the mass in an atom. Half-Life

Reading Essentials 37 What is the mass number? The mass number of an isotope is the number of neutrons plus protons. The ﬁgure below shows the mass number and particles for the isotopes of carbon. For example, carbon-12 has six protons and six neutrons, so its mass number is 12. Notice that all isotopes of carbon have six protons. The atomic number of carbon is 6.

Applying Math Isotopes of Carbon 1. Evaluate How many more neutrons does n-14 Carbon-14 have than Carbon-12? Mass number 4

Number of proto 6

Number of neutr 8

Number of electr 6

Atomic number 6

What is the strong nuclear force? How do you hold things together? You might use tape or glue. What holds the protons and neutrons together in the nucleus of an atom? Remember that protons have a positive charge. You might think that the protons would repel each other. But, when the protons and neutrons are tightly packed together in a nucleus, an even stronger binding force takes over. This force is called the strong nuclear force. The strong nuclear force keeps the protons from repelling each other. This force works only in the nucleus of an atom. 2. Explain What keeps the protons in an atom from Radioactive Decay repelling each other? The nuclei of most elements are stable because they have about the same number of protons as neutrons. For example, carbon-12 is stable because its atoms have six protons and six neutrons. Some nuclei are unstable because they have too many or too few neutrons. The particles in the nucleus try to repel each other. The nucleus must eject, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright or release, a particle to become stable. When a nucleus lets a particle go, it gives off energy. Radioactive decay is the release of particles and energy from the nucleus.

38 Inside the Atom Transmutation When protons are released from the nucleus, the atomic number of the atom changes. So one element changes into another. Transmutation is the changing of one element into another through radioactive decay. What happens when alpha particles are lost? 3. Explain What happens to an element if it Most smoke detectors contain the element americium-241 undergoes transmutation? (a muh RIH shee um). This element is unstable and undergoes radioactive decay. Americium-241 transmutates into another element by ejecting an alpha particle and energy. An alpha particle is a particle that is made up of two protons and two neutrons. The energy and alpha particle that are ejected are called nuclear radiation. In a smoke detector, the alpha particles make it possible for the air to conduct an electric current. As long as the electric current flows, the detector is silent. Smoke will interrupt the flow of the electric current and the alarm will go off. How does an element change its identity? Americium has 95 protons. After transmutation, it only has 93 protons and becomes the element neptunium. Neptunium has an atomic number of 93. Notice in the figure that the mass and atomic numbers of neptunium and the alpha particle add up to the mass and atomic number of americium. No particles were destroyed during transmutation.

95 p 93 p Applying Math 2 p 146 n 144 n 2 n 4. Calculate The element actinium has an atomic p n p number of 89. How many n alpha particles would Alpha americium need to lose particle before it became actinium?

Americium Neptunium

What are beta particles? Not all transmutations cause the nucleus to eject an alpha particle. Some eject an electron called a beta particle. A beta particle is a high-energy electron that comes from the

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright nucleus, not the electron cloud. But, the nucleus contains only protons and neutrons. How can it give off an electron? In this kind of transmutation, a neutron becomes unstable. It splits into an electron and a proton. The electron, or beta particle, is ejected with a large amount of energy.

Reading Essentials 39 What happens to the proton? After the electron is ejected, the proton stays in the nucleus. Now there is one more proton in the nucleus and the atomic number increases by one. The ﬁgure shows unstable hydrogen-3. One neutron splits into a proton and an electron. The electron (e–), or beta particle, is ejected. Now the nucleus has two protons. Hydrogen-3 turns into helium-3. The mass of the atom stays almost the same because the mass of the electron it loses is so small.

1 2 e Picture This 2 1 5. Identify Circle the beta particle in this diagram. Hydrogen-3 Helium-3 e

Rate of Decay Have you ever watched popcorn pop? You never know which kernel will pop next. But, if you have popped a lot of popcorn before, you might be able to predict how long it will take for half the kernels to pop. Radioactive decay also is random. That’s why radioactive decay is measured using its half-life. The half-life of a radioactive element is the amount of time it takes for half of a sample of the element to decay. How do you calculate half-life decay? The half-lives of radioactive isotopes range from fractions of a second to billions of years. Iodine-131 has a half-life of eight days. If you start with 4 g of iodine-131, after eight Applying Math days you have only half the amount, or 2 g. After eight more 6. Calculate If you start days, you have only 1 g. The radioactive decay of unstable with 4 g of iodine-131, how atoms happens at a steady rate that nothing can change. many grams would there be after 24 days? Show your How are objects dated using half-life? work. Scientists use radioactive decay to ﬁnd the age of fossils. Carbon-14 is a radioactive isotope of carbon. Its half-life is 5,730 years. It is used to ﬁnd the age of dead animals, plants, and humans. Living things have carbon-14 in them because

they take in and release carbon. When a living thing dies, the Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright amount of carbon-14 inside it begins to decrease because of radioactive decay. Scientists can measure the amount of carbon-14 in an ancient item. Using the half-life of carbon-14, scientists can calculate when the animal, plant, or human lived.

40 Inside the Atom Why are long half-lives sometimes a problem? Some radioactive isotopes have half-lives that are thousands, millions, or billions of years. Waste products that have these isotopes can be dangerous because they still release radiation. These waste products must be kept away from people and the environment. Special disposal sites are used to store this waste for long periods. Many of these sites are deep underground. Making Synthetic Elements There are only 92 elements found in nature. Other elements are made through transmutation. Scientists can smash alpha and beta particles into the nuclei of existing atoms to make new elements. Since these new elements are made by humans, they are called synthetic. Synthetic elements have greater numbers of protons and neutrons. They have atomic numbers greater than 92. What are the uses of radioactive isotopes? 7. Define What are synthetic elements? Scientists have made many useful isotopes. These isotopes, called tracer elements, can be placed in the body or released into the air. Then, scientists can use instruments to look for radiation while the tracer elements decay. Tracer elements have been used to diagnose diseases and study the environment. Tracer elements with short half-lives are the best to use. The short half-lives do not expose living organisms to radiation for long periods of time. Diagnose Diseases Iodine is an element that is used by the thyroid gland. Radioactive iodine-131 can be given to a patient with a thyroid problem. The tracer element is absorbed by the thyroid gland. The radiation can create a 8. Infer Why might we want picture of the thyroid. Doctors can then find out if the to know what happens to patient’s thyroid is working properly. pesticides in the environment? Study the Environment Tracer elements are used in the environment, too. Scientists inject them into the roots of plants to see how the roots absorb food. Others are put into pesticides. The tracer elements can then be followed to find out what happens to the pesticides in the environment. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 41 After You Read Mini Glossary atomic number: the number of protons in the nucleus of an mass number: the number of neutrons plus protons atom of an element radioactive decay: the release of particles and energy from half-life: the amount of time it takes for half of a sample of the nucleus the element to decay transmutation: the changing of one element into another isotopes: atoms of the same element that have different through radioactive decay numbers of neutrons

1. Review the terms and their deﬁnitions in the Mini Glossary. Explain why the mass number and atomic number of an element are different. Use complete sentences.

2. Complete the table to explain what causes radioactive decay and what happens when particles are ejected.

Radioactive Decay

Type of Particle Released Decay Process Result

Alpha particle The atom changes into a different element. The atom now has a lower atomic number.

Beta particle A neutron in the nucleus splits into a proton and an electron. The electron, or beta particle, is ejected. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about the nucleus of an atom. 42 Inside the Atom Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. displacement was12kmnortheast. Her and direction andendingpositions. between starting Displacement isthedistance position. herstart of northeast Thehiker’s endpositionwas12 km and stopping points. Thetotal distance traveled was22km. northeast. km and11 4kmsoutheast, She traveled 7kmnorth, Themapshows thepathtraveled by ahiker. object travels. Oneway to thepathan dothisisto describe position. you needto motion. beableto describe these questions, home andschool? Who isthefastest To runner? answer What are distanceanddisplacement? What are What ismotion? know thatyou have moved? how doyou When you walkfrom oneplace to another, section Another way motionisto to give describe onlythestarting by anobject how itchanges You motionof candescribe move?Does Earth What isthedistance between your chapter Read toLearn YouBefore Read 00 4 3 Also covers: Benchmarks—SC.C.1.3.1: ● SC.C.2.3.2; SC.C.2.3.6;SC.H.1.3.5 1 Forces andChangesinMotion Motion

N Start The studentknowsthatthemotionofanobjectcanbedescribedbyitsposition,directionmotion,andspeed. 2 km 0 1 Distance Finish acceleration. speed, velocity,and examples ofdisplacement, help youlearndeﬁnitionsand following four-tabFoldableto you highlighted. you ﬁnishreading,reviewwhat important inthissection.When sentences youthinkare to highlightwordsand ● Highlight A ■ ■ ■ What You’llLearn Classify and acceleration how tocalculatespeed and acceleration about speed,velocity, displacement about distanceand Reading Essentials Use ahighlighter Acceleration

Speed Velocity Make the 43 Relative Motion Something that is in motion changes its position. An object’s position is described in relation to another object, which is assumed to be not moving. The unmoving object is called the reference point. For example, you may look out the window in the morning and see a truck parked under a tree. In the afternoon, you see the truck parked farther down the block. The tree is the reference point, and the truck has moved relative to the position of the tree. Speed When you are moving, your position is changing. How quickly your position is changing is your speed. Speed is the distance traveled divided by the time needed to travel that distance. Speed increases if it takes less time to travel the same distance. The sprinter with the greatest speed in the 100-m dash is the sprinter who runs the 100-m in the shortest time. 1. Explain What increases What is constant speed? when more distance is covered in a given time? Have you ever been in a car with the cruise control on? The car’s speed does not change. This means the car’s speed is constant. Imagine a car is traveling at a constant speed of 30 m/s. This means that every second the car travels 30 meters. The speed does not change. When an object is traveling at a constant speed, its speed is the same at every instant. What is average speed? Does a car moving through the streets of a city have a constant speed? The car slows down or speeds up as trafﬁc lights change. It is not possible to drive at a constant speed in the city. The car’s instantaneous speed tells how fast the car is moving at a certain instant of time. A car’s speedometer shows its instantaneous speed. Average speed is another way to describe the motion of an object whose speed is always changing. Average speed is represented by the symbol v. Use the following equation to ﬁnd average speed:

distance (in m) Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright average speed (in m/s) time (in s) d v t

44 Forces and Changes in Motion Velocity Sometimes you might want to know the direction you are 2. Compare velocity to going as well as your speed. If so, you want to know your speed. How are they velocity. Velocity is the displacement divided by time. You different? can calculate velocity using the following equation: displacement velocity time Suppose you travel 1 km east in 0.5 hours. What is your velocity? (1 km east) Velocity (0.5 hours) 2 km/h east Your velocity is 2 km/h east. Remember that displacement is a distance and a direction. Velocity, like displacement, includes a direction. Airplane pilots need to know velocity. They need to know how fast and in what direction they are ﬂying. Acceleration Sometimes you need to know how motion changes, such as speeding up or changing direction. Acceleration is the change in velocity divided by the time it takes the change to occur. Because velocity includes both speed and direction, so does acceleration. If an object changes its speed, its direction, or both, it is accelerating. How can objects accelerate? 3. Describe what happens You may think that accelerate means to move faster. But when an object accelerates. slowing down is also acceleration. Why? Acceleration is a change in velocity. A change in speed is a change in velocity. So, slowing down is accelerating. How does turning relate to acceleration? Remember that when an object changes direction, its velocity changes. So, when an object changes direction, it is also accelerating. Imagine you are running a race around a track. Every time you follow the turn on the track, your direction changes. You are accelerating. At the end of the Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright race, you slow down and walk. Slowing down is accelerating. Any time velocity changes, acceleration occurs.

Reading Essentials 45 2. 1. speed: acceleration: Mini Glossary 3. 46 ____ the example. themotioninblankfront of Write theletter of column. in theright themotion theterm motionintheleftcolumn thatdescribes with Match theexample of term Write asentence usingthe Review theterms andtheirdefinitionsintheMini Glossary. ______thought were important. Did highlighting helpyou aboutmotion? learn Didhighlighting Why orwhy not? werethought important. you were asked words to highlight and sentences thatyou thesection, At of thebeginning After You Read Section End of Forces andChanges inMotion how quicklysomething’spositionchanges 1. 2. 5. 4. 3. velocity An airplane travelingAn airplane at200km/hnorth, A campermoves to anewcampsite A sailboatistraveling southeastat20km/h. un at butstays at200km/h. east, turns rvn o oa f6hours. foratotal of driving Lynn traveled 80kmeach hourwhile 30 km/h. He seesthatheistraveling speedometer. Jaime hisbike isriding andlooksathis herfirstcampsite. 8 kmsouthwest of a changeinthespeed,direction,orboth htsosyu nesadn ftheterm. that shows your understandingof xml Motion Example games, andprojectstohelpyou learnmoreaboutmotion. Visit velocity: fl7.msscience.com an object’sspeedanddirection a. e. d. c. b. instantaneous speed acceleration displacement average speed velocity to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. h aac emeet oc nhr pushing her upward. The balance beamexerts aforce onher, downward. pullsthegymnast Earth For example, objects. alsocanexert forces andEarth onother chairs, the floor, like Objects push orapullthatoneobjectexerts onanother. ttksaot3No oc olf a fsoftdrink. force to liftacanof It takes about3Nof aforce ismeasured (N). innewtons Thesize of push orpull. the aforce isthe direction of direction The of direction. aforce hasasize anda Just like velocity andacceleration, your push. force you apply andthedirection of amount of way The thebookmoves depends onthe notmove. will it thebook, you justashard pushdown onthe top of But if move itwill across thetable. push thebookfrom theside, theforces onher. acting nast changes becauseof thegym- these changes inmotionto occur? Themotionof What causes different movements to make theflipsmooth. actuallymakes many Thegymnast seem smoothandsimple. beam andlandperfectlyonthefloor?Her motionmay How is force measured? How isforce Force it?How doyou know this? you let goof What happento theballafter will throwingImagine aball. section mgn oki etn natbei rn fyu fyou If you. abookis restingImagine onatable infront of A aforce. An object’s motionchanges becauseof balance a Have flipbackward you off ever seenagymnast chapter Read toLearn YouBefore Read 4 3 Benchmarks—SC.C.1.3.1: Also covers: one forceactsonanobject,thentheforcescanreinforceorcanceleachother. ● 2 SC.A.1.3.2; SC.C.2.3.2;SC.C.2.3.6;SC.C.2.3.7;SC.H.1.3.5 Forces andChangesinMotion Forces andMotion The studentknowsthatmanyforcesactatadistance; SC.C.2.3.3 AnnuallyAssessed: f o r c e is a forces thataffectmotion. to helpyouidentifydifferent the followinghalf-bookFoldable ● Creating aQuiz to seeifyoulearnedthefacts. answer thequestionsasaquiz paper. Whenyoufinishreading, important factsonasheetof read, writequestionsabout B The studentknowsthatifmorethan What You’llLearn ■ ■ ■ Find MainIdeas Study Coach affect motion how differentforces how forcescombine what forceis Forces andMotion Reading Essentials As you Make 47 How Forces Combine Suppose you push on a door to open it. At the same time, 1. Apply If two people are someone else pushes on the other side of the door. How will pushing at a door from opposite directions, what the door move? Will it move in the direction that you are must one person do to pushing? More than one force is acting on the door. The push open the door from net force is the combination of all the forces acting on an his or her side? object. The net force on the door comes from the two pushes on the door. How do forces in the same direction combine? Imagine you and a friend are trying to move a couch. You both push on the same side of the couch. The net force is a combination of both your pushes. You exert a force of 15 N to the left, and your friend exerts a force of 10 N to the left. The net force is 25 N to the left. How do forces with opposite directions combine? Imagine you are pushing on a door with a force of 5 N to the left. Someone else pushes on the door with a force of 8 N to the right, as in the figure below. The forces combine to form a net force. As you can see, the net force is 3 N to the right. When two forces are in opposite directions, the net force is the difference between the two forces. The net force is in the direction of the larger force. What would happen if both people pushing on the door exerted 8 N of force, in opposite directions? The two forces have equal strength. If two forces of equal strength act on an object in opposite directions, then the net force is zero.

5 newtons 5 newtons

Picture This 2. Label each set of pictures, showing in which set the box Moves a Lot, Moves a Little, or Does Not Move. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

48 Forces and Changes in Motion Balanced and Unbalanced Forces In a game of tug of war, two teams pull on a rope in opposite directions. If both teams pull with the same force, the net force is zero. The motion of the rope does not change. The forces acting on an object are balanced forces if the net force is zero. Balanced forces do not change the motion of an object. What happens if one team pulls harder on the rope? Then the net force on the rope is not zero. The forces acting on an object are unbalanced forces if the net force is not zero. The motion of an object will change only if the forces acting on it are unbalanced forces. Unbalanced forces cause an object to speed up, slow down, or change direction. Contact and Non-contact Forces A force is exerted when one object pushes or pulls on another. Your ﬁngers exert a force on a pencil when you write. Your ﬁngers have to be touching the pencil to exert a force. A contact force is a force that is exerted only when two objects are touching. Other forces can be exerted by one object on another even when the objects are not touching. Suppose you rub two balloons on a sweater, and then bring them close together? The balloons push each other away. Each balloon exerts an electric force on the other, even though they are not touching. Electric forces, magnetic forces, and gravity are non-contact forces. Non-contact forces are forces that can be exerted by one object on another even when the objects are not touching.

Gravity 3. Apply If you hold a magnet near some paper Gravity is a non-contact force that every object exerts on clips, the paper clips will be every other object due to their masses. You and Earth exert pulled towards the magnet. gravitational forces on each other. Is this an example of a contact force or a non- Gravity is an attractive force that pulls objects closer contact force? Explain together. If you jump up, gravitational force will pull you down. The size of the force depends on the masses of the objects and the distance between them. The gravitational Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright force between two objects increases if the mass of one or both of the objects increases or if they move closer together.

Reading Essentials 49 How do mass and weight relate to gravity? Earth’s gravity exerts a force on an object, pulling it toward Earth. This force is the weight of an object. Because weight is a force, it is measured in units called newtons. Mass is the amount of matter an object contains, so mass is measured in kilograms. The mass of an object may not change, but its weight does change if its distance from Earth changes or if it’s on a planet with a force of gravity different from Earth’s. The gravitational force Earth exerts on an object is the weight of the object. Because weight is a force, it is measured in newtons. Weight is not the same as mass. Mass is the amount of matter an object contains and is measured in kilograms. The mass of an object doesn’t change. The weight of an object will change if its distance from Earth changes. 4. Explain how an object’s weight can change even Friction though its mass stays the same. Push your hand across a desk top. Is it hard to move your hand across the desk? Maybe there is some resistance, and it feels like something is pushing back. That resistance is the force of friction beween your hand and the desk. Friction is a contact force that resists the sliding motion of two surfaces that are touching. Friction causes a sliding object to slow down and stop. Friction also can prevent surfaces from sliding past each other. What is static friction? Imagine you are trying to push a box ﬁlled with books. You apply a force to the box, but the box still does not move. Because there is no change in the box’s motion, the net force must be zero. The ﬁgure below shows this. The force you are exerting on the box is balanced by another force on the box in the opposite direction. Static friction is Picture This the force between two surfaces in contact that keeps them 5. What is the force that prevents the person from sliding when a force is applied. pushing the box from moving it? Net force = 0 Force 1 Force 2 Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

50 Forces and Changes in Motion What is sliding friction? If you push hard enough on the box of books, it will start to slide. If you stopped pushing the box, it would slide a little more and then come to a stop. Sliding friction is a force that opposes the motion of two sliding surfaces in contact. Sliding friction exists between any sliding surfaces that are touching. There is sliding friction as a book moves across a table. There is sliding friction between the moving parts in a car’s engine. What causes friction? All surfaces are covered with tiny dips and bumps. When two surfaces meet, they stick together where these dips and bumps come into contact. Friction is caused by the sticking 6. Contrast sliding friction of two surfaces at these dips and bumps. and static friction. How are Static friction happens when the force on an object they different? cannot overcome this sticking. Once enough force is applied, the sticking connections are broken and the object can be moved over the surface. The Buoyant Force The force that is exerted by a fluid on an object that is in the fluid is called the buoyant force. The buoyant force is always an upward force. When you float in a pool of water, the buoyant force is large enough to balance your weight. Air Resistance If you drop a flat sheet of paper and a crumpled sheet of paper at the same time, the crumpled paper falls faster. Air resistance is a contact force that opposes the motion of objects moving in air. Air resistance is a force that pushes up on a falling object. Like friction, it acts in the direction opposite to the object's motion. The air resistance on a flat sheet of paper is larger than Picture This the force of air resistance on a crumpled sheet. The size of 7. Draw and Label What would the forces on the the air resistance force depends on the shape and speed of skydiver look like if the the object. Air resistance is greater on a wide, flat object than parachute did not open? on a narrow, pointed one. Draw an arrow labeled Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Parachutes increase the amount of air resistance on a “air resistance” and an arrow labeled “gravity,” to show skydiver. Air resistance on the parachute becomes large enough the size of the air resistance to balance the gravitational force on the skydiver. Air resistance compared to the force reduces the skydiver’s speed so that he can land safely. of gravity.

Reading Essentials 51 After You Read Mini Glossary air resistance: a contact force that opposes the motion of gravity: a non-contact force that every object exerts on objects moving in air every other object due to their masses balanced forces: forces that are equal, but in opposite net force: the combination of all the forces acting on an directions so the net force is zero object contact force: a force that is exerted only when two objects non-contact force: force exerted by one object on another are touching even when the objects are not touching force: a push or a pull that one object exerts on another unbalanced forces: unequal forces acting on an object so friction: a contact force that resists the motion of two sur- the net force is not zero faces that are touching

1. Review the terms and their deﬁnitions in the Mini Glossary. Explain the difference between contact and non-contact forces.

2. On the lines, label each ﬁgure below with the terms balanced forces or unbalanced forces to show whether the forces acting on each object are balanced or unbalanced. If the forces are unbalanced, use an arrow to show the direction of the greatest force.

b. d.

3. How could you use a shopping cart to show balanced and unbalanced forces to a group of elementary students? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about forces and motion. 52 Forces and Changes in Motions chapter Forces and Changes in Motion 0043 section ●3 The Laws of Motion Benchmarks—SC.C.2.3.5 Annually Assessed: The student understands that an object in motion will continue at a constant speed and in a straight line until acted upon by a force and that an object at rest will remain at rest until acted upon by a force.

Before You Read What You’ll Learn ■ how net force, mass, How do you know how hard to kick a ball to get it to a friend? and acceleration are related ■ what action and reaction forces are

Read to Learn Study Coach Identifying the Main Newton’s Laws of Motion Point As you read, write down Changes in motion of all objects are caused by forces. the main point or idea of each paragraph. After you finish Forces act on galaxies, planets, and cars on the street. How reading, make sure you do the forces that act on an object change an object’s understand each main point. motion? There are three rules that can help you understand changes in motion. These rules are known as Newton’s laws of motion. Isaac Newton presented these laws in 1687. These laws apply to all objects. They can predict the motion of planets in the solar system and describe the motion of a skateboard. First Law of Motion How can an object move if the forces acting on it are balanced? The first law of motion states that if the forces acting on an object are balanced, then an object at rest remains at rest and an object in motion keeps moving in a straight line with constant speed. In other words, when forces acting on an object are balanced, the object’s motion doesn’t change. ●C Find Main Ideas Make For an object to change speed or direction, the net force the following half-book Foldable to help you identify the main acting on it must not be zero. For example, if you throw a ideas of Newton’s first law

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright ball, it eventually changes direction after it leaves your hand. of motion. When it leaves your hand, the net force on the ball is not zero. Gravity exerts a force on the ball. The force of gravity Newton's is the unbalanced force that changes the ball’s direction, First Law of Motion pulling it toward the ground.

Reading Essentials 53 Why do objects change speed? You make a skateboard speed up by pushing it in the direction it is moving. If the net force acting on an object is in the same direction the object is moving, the object will speed up. If the net force acts in the direction opposite to an object’s motion, the object slows down and moves in a straight line. Why do objects change direction? In the ﬁgure below, the basketball player expects the ball to go up, then curve down and through the hoop. He throws the ball up, but after the ball leaves his hands, it does not go up forever. It changes direction. An unbalanced net force, gravity, acts on the ball. Because of the force of gravity, the path of the basketball curves downward and goes through the hoop. Picture This 1. Explain the difference between what the dotted line represents and what the solid line reprsents in the picture.

Doug Menuez/PhotoDisc

F T OC A U C Annually Assessed

S F Benchmark Check The Second Law of Motion SC.C.2.3.5 You have learned that an object is accelerating when it ✔ 2. List the two factors speeds up, slows down, or changes direction. Newton’s that determine an second law of motion describes how the net force on an object’s acceleration. object, the mass of an object and the acceleration of the object are related. When you lift your backpack, you cause the backpack to speed up and accelerate. The second law of motion states that the acceleration of an Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright object depends on the net force acting on the object and the object’s mass.

54 Forces and Changes in Motion How are acceleration and mass related? It is easier to throw a baseball than a basketball because the baseball has a smaller mass. If you apply the same ●D Classify Make the following quarter-fold Foldable amount of force to the baseball and the basketball, the to organize information about baseball will have more speed. Acceleration is larger when Newton’s second law. the speed of an object changes more quickly. Second Law Acceleration The same net force affects a baseball and a basketball and Mass

differently. If the net force is the same as the mass of an Newton's Second object increases, acceleration decreases. If you lift an empty Law Direction of Size of Force backpack and one that is full of books with the same force, Force the empty one will accelerate more quickly.

The same applies to lifting a backpack. If your backpack is Closed Open empty, you can lift it easily and quickly with little force. But suppose your backpack is ﬁlled with textbooks. Then you will have to apply a lot of force to lift the backpack. The book-ﬁlled backpack has more mass than an empty backpack. If you lift a full backpack with the same force as you would an empty backpack, you will not be able to lift it very quickly, if at all. The mass of the backpack determines how much force you must apply to lift it. How does direction of net force affect acceleration? 3. Explain what you need to The second law of motion states that an object’s acceleration do to pick up a backpack is in the same direction as the force applied to it. When you quickly. pull on a wagon, it moves in the same direction as your pull. When a tennis player serves a ball, the ball changes direction and moves in the direction of the force from the racket. If a soccer ball rolls toward you, you can stop it with your foot. The force of your foot is opposite to the motion of the ball, so the ball slows and stops. When an object slows down, the direction of its acceleration is opposite to its direction of motion. The acceleration of the ball is still in the direction of the net force on the ball. How does the size of force affect an object's acceleration? When you apply enough force to lift your backpack, the backpack accelerates. Its speed depends on its mass and also on the force you exert on the backpack. If you apply more 4. Explain how acceleration Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright force, the speed of the backpack changes more quickly. The and net force are related. greater the force, the larger the acceleration of the backpack. The second law of motion explains that the acceleration of an object increases when the net force on the object increases.

Reading Essentials 55 The Third Law of Motion ●E Organize Information How high can you jump? Think about the forces acting Make the following Foldable to on you when you jump. Gravity is pulling you downward. gather information about Where does the upward force come from? Part of the Newton’s third law of motion. upward force comes from your legs and feet pushing you up. Part of the force also comes from the ground, which Third Law Force Pairs pushes you up. Newton's third law of motion states that when one object exerts a force on a second object, the second object exerts Action Combine Reaction the Laws an equal force in the opposite direction on the ﬁrst object. In the ﬁgure below, the person’s feet are pushing down on the ground. The ground is pushing up on her. This upward force the ground exerts allows the jumper to leave the ground for an instant.

Richard Hutchings Picture This What are force pairs? 5. Draw and Label Force pairs are the forces two objects exert on each other. Forces a. What would the force In the ﬁgure above the girl is pushing down on Earth when pair on the diagram above she jumps, and Earth is pushing up on her. These two forces look like if the girl tried to are a force pair. They are equal even though they push in jump higher? Draw the opposite directions. What if the girl wants to jump higher? arrows and label them. b. Are there any other She has to push harder on the ground. Then the ground forces acting on the girl as will push up harder on her. she jumps? Draw and label You might think that the forces in a force pair cancel one other force, using an out because they are equal and in opposite directions. But arrow to show its direction. remember that the two forces are acting on different objects. One force is acting on the girl, and the other force is acting Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright on Earth. Force pairs don’t cancel out because they act on different objects. Equal and opposite forces cancel out only if they act on the same object.

56 Newton’s Laws of Motion What are action and reaction forces? The third law of motion says that forces act in pairs. When you push on a wall, the wall pushes back on you. 6. Apply Use what you One force is called the action force. The other force is the know about Newton’s third law to explain how ﬂippers reaction force. Your push on the wall is the action force. The help swimmers move wall pushing back is the reaction force. Every action force through the water. has a reaction force that is equal in size, but in the opposite direction. Newton's third law explains how a swimmer moves through the water. The swimmer’s hands exert a backward force on the water creating an action force. The water then exerts a forward reaction force pushing the swimmer forward. Combining the Laws The laws of motion describe how the motion of any object changes when forces act on it. This is true of the space shuttle. Newton’s third law states that every action has an equal and opposite reaction. That is why a huge force from its rocket engines is required to lift the space shuttle into the atmosphere. The rocket engines give off gasses that push down against the ground with tremendous force. The reaction is that the shuttle lifts off, or moves away from Earth and its gravitational force. Basketball Application When a basketball player pushes down 7. Recall Which law of on the ground, the third law of motion states that the ground motion is demonstrated by a shuttle lift off? pushes up on the basketball player. If the basetball player pushes hard enough, the downward force of gravity and the upward push from the ground combine to produce a net force on him or her that is upward. According to the second law of motion, the basetball player accelerates upward. When the basketball player is in the air the downward force of gravity is acting in a direction opposite to the player’s direction of motion. This causes the basetball player to slow down until he or she reaches the top of the jump. Then, as the basetball player starts moving downward, gravity is working in the same direction as the player’s motion, so the basketball player speeds up as he or she falls. When the basketball player hits the ground, the upward

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright force exerted by the ground brings the player to a stop. Then the forces acting on the basetball player are balanced, and the player remains at rest.

Reading Essentials 57 After You Read Mini Glossary ﬁrst law of motion: an object will remain at rest, or keep third law of motion: when one object exerts a force on a moving in a straight line with constant speed, unless second object, the second object exerts an equal force in an unbalanced force acts on it. the opposite direction on the ﬁrst object second law of motion: the acceleration of an object depends on the net force acting on an object, and the object’s mass

1. Review the terms and their deﬁnitions in the Mini Glossary. State each of the laws of motion in your own words.

First Law:

Second Law:

Third Law:

2. Look at the ﬁgure. Using the third law of motion, identify and label the action and reaction forces that are applied to each object as the bowling ball hits the pin.

a. b.

3. At the beginning of this section, you identiﬁed the main point of each paragraph. How did this help you understand the information in this section? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about Newton’s laws of motion. 58 Forces and Changes in Motion chapter Work and Simple Machines 0053 section ●1 Work and Power Benchmarks—SC.C.2.3.4: The student knows that simple machines can be used to change the direction or size of a force. Also covers: SC.H.1.3.4; SC.H.1.3.5; SC.H.1.3.6; SC.H.3.3.5

Before You Read What You’ll Learn ■ when work is done When you think of work, you might think of household ■ how to calculate how chores, homework, or an after school job. Describe the work much work is done you have done today. ■ how work and power are related

Read to Learn Study Coach Make Flash Cards After What is work? you read each page, write two quiz questions on flash cards. In science, there is a special definition of work. Work is Write a question on one side of done when a force makes an object move in the same each flash card. Write the answer direction as the force that is applied. You do work when on the other side. Quiz yourself you lift your books, turn a doorknob, or write with a pen. until you know the answers. What does motion have to do with work? Suppose your teacher asks you to move a box of books. You try, but the box will not move. It is too heavy. You are tired because you tried to force the box to move. But you have not done any work. Two things must happen for you to do work. First, you must apply a force on an object. Second, the object must move in the same direction as the force that you applied. Imagine a girl standing still and holding two bags of groceries. Is she doing work? No, she is not moving or causing anything to move. How does the direction of force affect work? ●A Organize Information Your arms apply a force upward when you lift a box. Make the following Foldable to Your arms did work because the basket moved in the same help you understand work and direction as the force your arms applied. If you walk with power. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright the box, your arms are still applying an upward force on it. But you and the box are moving. The box is not moving What What in the same direction as the upward force your arms is work? is power? applied. So, no work is done by your arms.

Reading Essentials 59 Does all of a force do work? Sometimes only part of a force moves an object. Think about what happens when you push a lawn mower. Look at the ﬁgure below. You push at an angle to the ground. Part of the force is forward. Part of the force is downward. Which part of the force does work? Only the part of the force that is forward does work because it is in the same direction as the motion of the mower.

Picture This 1. Identify Which force in the ﬁgure does work? Circle the label and arrow. Forward force

Total force

Downward Motion Force

Calculating Work Work is done when a force makes an object move. More work is done if the force is increased or if the object moves farther. You can calculate how much work is done by using the work equation below. The SI unit for work is the joule (JEWL). The joule is named for the nineteenth-century scientist James Prescott Joule. Applying Math Work Equation 2. Calculate A woman work (joules) force (newtons) distance (meters) lifted a box with a force of W Fd 50 N. She lifted the box 2 m. How much work did she do? Show your work. What distance is used for the work equation? Suppose you give a book a push and it slides across a table. You use the distance an object moves while a force is Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright acting on it to calculate work, not the total distance the object moved. So, the distance in the work equation is the distance the book moved while you were pushing it.

60 Work and Simple Machines What is power? What does it mean to be powerful? Imagine two weightlifters lifting the same amount of weight. They lift the weight the same distance above the ﬂoor. They both do the same amount of work. But the amount of power they use depends on how long it took to do the work. Power is how quickly work is done. The weightlifter who lifted the weight in less time is more powerful. How do you calculate power? You can calculate power by dividing the amount of work done by the time needed to do the work. work (joules) power (watts) Applying Math time (seconds) 3. Calculate A teacher does W P 140 J of work in 20 s. How t much power in watts did he use? Show your work. The SI unit of power is the watt. The watt is named for James Watt, a nineteenth-century British scientist. How can doing work change energy? Remember that when something moves, it has kinetic energy. If you push a chair and make it move, you do work on the chair. You also change the chair’s energy. By making the chair move, you increase the chair’s kinetic energy. If you lift an object higher, you also change the energy of the object. The potential energy of an object increases when it is higher above Earth’s surface. When you lift an object, you do work on the object and increase its potential energy. How are power and energy related? 4. Summarize When you do work on an object, what You increase the energy of an object when you do work on two kinds of energy can you it. Because energy cannot be created or destroyed, the object increase for the object? gains energy while you lose energy. When you do work on an object, you move, or transfer, energy to the object and your energy decreases. The amount of work done is the amount of energy transferred to the object. So, power is also equal to the amount of energy transferred in a certain amount of time. Sometimes energy can be transferred even when no work is done. This happens when heat ﬂows from a warm object

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright to a cold one. Energy can be transferred in many ways, even when no work is done. Power is always the rate, or speed, at which energy is transferred. The rate is the amount of energy transferred divided by the time needed to transfer it.

Reading Essentials 61 After You Read Mini Glossary power: the rate at which work is done work: a force makes an object move in the same direction as the force that is applied

1. Read the key terms and deﬁnitions in the Mini Glossary above. Describe work in your own words.

2. Complete the table.

How did the action Was work done In which direction Action change the energy on the book? was work done? of the object?

Increases the potential Lifting your books from yes up and kinetic energy as the bottom of your locker they are lifted.

Carrying your books from your locker to class

Pushing your book across your desk for a friend to see

3. You were asked to make two ﬂash cards for every page of the section. How did this help you learn the material in the section? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about work and power. 62 Work and Simple Machines chapter Work and Simple Machines 53 section ●2 Using Machines Benchmarks—SC.C.2.3.4: The student knows that simple machines can be used to change the direction or size of a force.

Before You Read What You’ll Learn ■ how a machine makes Describe a machine you used today and tell what it does. work easier ■ about mechanical advantage and efﬁciency ■ how friction reduces efﬁciency

Read to Learn Locate Information What is a machine? Highlight each head that asks a question. Then, use a different You may think of a machine as a car or an appliance. color to highlight the answers to Scissors, brooms, and knives are all machines, too. A the questions. machine is a device that makes doing work easier. Even a sloping surface can be a machine. Mechanical Advantage Machines change the way you do work. When you use a machine, you apply a force over a distance. You use force to move a rake or lift the handles of a wheelbarrow. Input force is the force that you apply on a machine. The work you do on a machine is equal to the input force times the distance over which your force moves the machine. The work that you do on the machine is the input work. The machine also does work. It applies a force to move ●B Organize Information an object over a certain distance. Output force is the force Make the following Foldable to that the machine applies. A rake, for example, applies a help you organize information force to move leaves. The work that the machine does is the about machines, mechanical output work. advantage, and efﬁciency. When you use a machine, the output work can never be

greater than the input work. So why use a machine? A What is a machine?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright machine can make work easier in three ways because it can:

What is • change the amount of force you need to apply. mechanical advantage? • change the distance over which the force is applied. What is • change the direction in which the force is applied. efficiency?

Reading Essentials 63 How does changing force make work easier? Some machines make work easier by reducing the force you need to apply. This kind of machine increases the input force so the output force is greater than the input force. You Applying Math need less force to do the work. The mechanical advantage (MA) of the machine is the number of times that a machine 1. Calculate Suppose you use a machine to move a increases the input force. You can calculate mechanical large rock. You apply a advantage using this equation: force of 100 N to the output force (newtons) machine. The machine mechanical advantage applies a force of 2,000 N to input force (newtons) the rock. What is the F MA out mechanical advantage of F the machine? Show your in work. How does changing distance make work easier? Some machines let you apply force over a shorter distance. In these machines, the output force is less than the input force. A rake is an example of this kind of machine. You move your hands a small distance at the top of the handle. But, the bottom of the rake moves a greater distance. The mechanical advantage of this kind of machine is less than one because the output force is less than the input force. Picture This Does changing direction make work easier? 2. Describe Write the Sometimes it is easier to apply a force in a certain direction. words that make the Imagine putting a flag up on a flagpole. It is easier to pull sentence true: When a down on the rope on the flagpole than to pull up on it. Some machine increases a. , it is applied machines let you change the direction of the input force. In over a shorter b. . these machines, the distance and the force do not change. The mechanical advantage of this kind of machine is equal to one. a. ______The output force is equal to the input force. The figures show b. ______the three ways machines make doing work easier.

Larger force Force applied over applied over Changes Input force same distance Input force Increases a shorter direction in a different force distance of force direction

Smaller force Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright applied over Input force Increases a longer distance distance

64 Work and Simple Machines Efficiency A machine can make the output force greater than the input force, but it can’t make the output work greater than the input work. There is friction when parts of the machine move. Friction always changes some of the input work into thermal energy. So, the output work is less than the input work. If friction in the machine decreases, the efficiency of the machine increases. The efficiency of a machine is the ratio of the output work to the input work. You can find Applying Math efficiency by using this equation: 3. Calculate Workers use a ramp to load a piano into a output work (joules) efficiency (in percent) 100% truck. The output work, or input work (joules) the amount of work needed to move the piano, is Wout 12,000 J. The workers do eff 100% 15,000 J of work. What is Win the efficiency of the ramp? How does friction affect a machine? Show your work. Imagine pushing a heavy box up a ramp. The bottom surface of the box slides across the top surface of the ramp. Neither the box nor the ramp is perfectly smooth. Each surface has high spots and low spots. As the two surfaces slide past each other, high spots on the two surfaces touch each other. The places that they touch are called contact points. At these contact points, atoms and molecules can bond together. This makes the contact points stick together. The attractive forces between all of the bonds added together is the frictional force. The frictional force tries to keep the two surfaces from sliding past each other. To keep the box moving, a force must be applied. The 4. Identify What causes force has to break the bonds between the contact points. friction? Even after these bonds are broken and the box moves, new bonds form as different parts of the two surfaces touch. How can friction be reduced? One way to reduce friction between two surfaces is to add oil to the surfaces. Oil can fill the gaps between the surfaces. Oil keeps many of the high spots from touching each other. There are fewer contact points between the surfaces. So, the

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright force of friction is less. This means more of the input work is changed to output work by the machine.

Reading Essentials 65 After You Read Mini Glossary efﬁciency: the ratio of the output work to the input work mechanical advantage: the number of times that a input force: the force that you apply on a machine machine increases the input force output force: the force that a machine applies

1. Review the terms and their deﬁnitions in the Mini Glossary. Describe one of the ways a machine makes work easier.

2. In the ﬁgure below, write how each machine makes doing a job easier. Write the terms increases force, changes direction of force, and increases distance in the correct locations. How Machines Make Work Easier

Force applied over Input force same distance in a different direction

Smaller force Input force applied over a longer distance

Larger force Input force applied over a shorter distance

3. How did highlighting the answers to the headings that were questions help you make sure you understood the material in the section? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about using machines. 66 Work and Simple Machines chapter Work and Simple Machines 53 section ●3 Simple Machines Benchmarks—SC.C.2.3.4: The student knows that simple machines can be used to change the direction or size of a force. Also covers: SC.H.1.3.5; SC.H.2.3.1

Before You Read What You’ll Learn ■ what the different Suppose you need to put a heavy box into a truck. Would simple machines are you rather push the box up a ramp or lift it straight into ■ how to ﬁnd the the air? Explain. mechanical advantage of each simple machine

Read to Learn Identify Simple What is a simple machine? Machines As you read through this section, underline In the last section you learned that machines make work each kind of simple machine. easier. Some machines like cars, elevators, or computers are very complicated. But machines can be very simple. A hammer, a shovel, and a ramp are all machines. A simple machine is a machine that does work with only one movement. The six simple machines are the inclined plane, lever, wheel and axle, screw, wedge, and pulley. A compound machine is a machine made up of more than one simple machine. A bicycle and a can opener are compound machines. Inclined Plane Ramps have been used for thousands of years. Ancient Egyptians might have used them to build their pyramids. ●C Compare and Contrast Make the following Foldable to Archaeologists hypothesize that the Egyptians built huge compare and contrast simple ramps to move limestone blocks. The blocks each weighed and compound machines. more than 1,000 kg. A ramp is a simple machine known as an inclined plane. Simple

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright An inclined plane is a ﬂat, sloped surface. You might need a Machines lot of force if you have to lift an object. An inclined plane Both lets you use less force to move an object from one height to Compound another. The longer the inclined plane, the smaller the force Machines needed to move the object.

Reading Essentials 67 Weight = 1,500 N

Force = 300 N

1 m Force = 1,500 N 5 m

Picture This How are inclined planes used? 1. Evaluate Circle the force Suppose you have to lift a box weighing 1,500 N into a needed to push the box up truck that is 1 m off the ground. Could you do that? The the ramp. Then, circle the force (1,500 N) times the distance (1 m) equals 1,500 J of force needed to lift the box straight up. How much work. Look at the figure. Suppose you use a 5-m-long ramp more force is needed to lift to move the box into the truck. The amount of work you the box straight up? need to do is still 1,500 J of work. But, the distance over which you apply the force is now 5 m. When you divide both sides of the work equation by distance, you have an equation for finding force. work (joules) Force distance (meters) 1,500 J Force 300 N 5 m When you use the ramp, you need to apply a force of only 300 N. A force of 300 N is much less than a force of 1,500 N. With the ramp, you apply the force over a distance that is five times longer. So, the force is five times less. The mechanical advantage of an inclined plane is the length of the inclined plane divided by its height. In this example, the ramp has a mechanical advantage of 5. What is a wedge?

A wedge is an inclined plane that moves. A wedge can Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright have one or two sloping sides. A knife is an example of a wedge. An axe and certain kinds of doorstops also are wedges. The mechanical advantage of a wedge increases as the wedge becomes longer and thinner.

68 Work and Simple Machines Are there wedges in your body? You have wedges in your body. Think of biting into an apple. The bite marks on the apple show that your front teeth are wedge-shaped. A wedge changes the direction of the applied force. The downward force of your bite is changed into a sideways force. The sideways force pushes the skin of the apple apart. Is a screw an inclined plane? The screw is another form of inclined plane. A screw is T FO A C an inclined plane wrapped around a cylinder or post. The U C

S inclined plane on a screw forms the threads of the screw. A F Benchmark Check screw changes the direction of the applied force. The applied SC.C.2.3.4 force pulls the screw into the material. Friction between the ✔ 2. Explain What threads and the material holds the screw tightly in place. holds a screw into an The mechanical advantage of the screw is the length of the object? inclined plane wrapped around the screw divided by the length of the screw. The more tightly wrapped the threads are, the easier it is to turn the screw. Lever A lever is any rigid rod or plank that pivots, or rotates, around a point. The fulcrum is the point that the lever pivots around. You can ﬁnd the mechanical advantage of a lever by dividing the distance from the input force to the fulcrum by the distance from the fulcrum to the output force. This is shown in the ﬁgure below.

Input Output force force Mechanical 10 cm 1 == advantage 50 cm 5 10 cm 50 cm Picture This 3. Calculate The distance from the input force to the fulcrum is 60 cm. The Input Output distance from the fulcrum force force Mechanical 50 cm ==5 to the output force is 20 cm. advantage 10 cm What is the mechanical 50 cm 10 cm advantage of this lever? Show your work. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright The fulcrum of a lever can be in different positions. When the fulcrum is closer to the output force than the input force, the mechanical advantage is greater than 1. Scissors, a wheelbarrow, and a baseball bat are all levers.

Reading Essentials 69 Wheel and Axle Imagine a doorknob the size of a pencil. Would it be easy to turn? No, it would be hard to turn. A doorknob is a simple machine that makes opening a door easier. A doorknob is a wheel and axle. A wheel and axle is two circular objects of different diameters attached so that they rotate together. The larger object is the wheel and the smaller object is the axle. If the input force is applied to the wheel, the output force is exerted by the axle. In this case, the mechanical advantage is equal to the diameter of the wheel divided by the diameter of the axle. The handle on the water faucet in the ﬁgure below is a wheel and axle. The faucet handle has a large diameter and is the wheel. The axle is the shaft the handle is attached to.

Wheel Picture This Axle 4. Analyze Does the wheel Input or the axle of the faucet force exert the output force?

Output force

How are wheel and axles used? In some wheel and axles, the input force turns the wheel. The wheel turns the axle. The turning axle exerts the output Applying Math force. The mechanical advantage is greater than 1 because 5. Calculate A wheel has a the wheel is bigger than the axle. This means the output force diameter of 15 cm. The axle is greater than the input force. A doorknob, a steering wheel, has a diameter of 3 cm. What is the mechanical and a screwdriver are examples of this type of wheel and axle.

advantage of the wheel and In other wheel and axles, the input force is applied to Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright axle? Show your work. turn the axle and the output force is exerted by the wheel. The mechanical advantage is less than 1. The output force is less than the input force. A fan and a Ferris wheel are examples of this type of wheel and axle.

70 Work and Simple Machines Pulley To raise a sail, a sailor pulls down on a rope. The rope uses a simple machine called a pulley to change the direction of the force used. A pulley is a grooved wheel with a rope or cable wrapped over it. What is a fixed pulley? Think about the pulley on a sail. The pulley is attached to something above your head. This kind of pulley is called a fixed pulley. When you pull down on the rope, the sail is pulled up. Look at the figure of the fixed pulley below. A fixed pulley does not change the force you apply. It also does not change the distance over which you apply a force. A fixed pulley does change the direction in which you apply your force. The mechanical advantage of a fixed pulley is 1. What is a movable pulley? You can also attach a pulley to the object you need to lift. This is called a movable pulley. A movable pulley lets you apply a smaller force to lift the object. The mechanical advantage of a movable pulley is always 2. The middle Picture This pulley in the figure below is a movable pulley. 6. Explain How does a You often will see movable and fixed pulleys used movable pulley change the together. This is called a pulley system. The mechanical input force? advantage of a pulley system is equal to the number of sections of rope pulling up on the object. The mechanical advantage for the pulley system in the figure is 3.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright A fixed pulley changes A movable pulley A pulley system uses the direction of the multiplies the more than one pulley to input force. input force. increase the mechanical advantage. Fixed pulley Movable pulley Pulley system

Reading Essentials 71 After You Read Mini Glossary compound machine: a machine made up of more than one screw: an inclined plane wrapped around a cylinder or post simple machine simple machine: a machine that does work with only fulcrum: the point that a lever pivots around one movement inclined plane: a ﬂat, sloped surface wedge: an inclined plane that moves lever: any stiff rod or plank that turns around a point wheel and axle: two round objects of different sizes that pulley: a grooved wheel with a rope or cable wrapped over it are attached so they turn together

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence describing how a screw and a wedge are related.

2. Match each simple machine with the correct example. Write the letter of each simple machine in Column 2 on the line in front of the example it is or uses in Column 1. Column 1 Column 2 1. tooth a. inclined plane 2. doorknob b. wheel and axle 3. threads of a lightbulb c. wedge 4. wheelbarrow d. screw 5. ramp e. pulley 6. ﬂagpole f. lever

3. What would be a good way to teach an elementary science class about simple machines? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about simple machines. 72 Work and Simple Machines chapter Energy and Energy Resources 63 section ●1 What is energy? Benchmarks—SC.A.2.3.3 Annually Assessed: The student knows that radiation, light, and heat are forms of energy …; SC.H.1.3.5 Annually Assessed: The student knows that a change in one or more variables may alter the outcome of an investigation. Also covers: SC.A.1.3.3; SC.B.1.3.1; SC.B.2.3.1

Before You Read What You’ll Learn ■ what energy is What does the phrase “She has a lot of energy” mean to you? ■ the difference between kinetic energy and potential energy ■ about the different forms of energy

Read to Learn Highlight As you read this The Nature of Energy section, highlight the different forms of energy. Then write an Energy is the ability to do work. An object that has example of each type of energy energy can make things happen or make things change. next to the places you Look around you and notice the changes that are highlighted. happening. Sunshine might be warming your desk. Maybe you can see the wind moving the leaves on a tree. When is energy noticed? You have a lot of energy. So does everything around you. But you only notice this energy when a change takes place. When a change happens, energy is transferred, or moved, from one object to another. Energy from sunlight transfers to the spot on the desktop and makes it warm. Energy from the wind is transferred to the leaves. All objects, including desktops and leaves, have energy. Kinetic Energy When an object is moving, it can do work and cause change. Suppose a bowling ball rolls down the alley and ●A Organize Information Make the following Foldable to knocks down some bowling pins. A change happens when the organize information about the pins fall over. The bowling ball causes this change. Because nature of energy, the energy of energy is the ability to do work or cause change, the bowling position, and the different forms Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright ball has energy. The energy in the moving ball makes the pins of energy. fall. The energy an object has because of its motion is kinetic energy. So as a bowling ball moves, it has kinetic energy. If an object is not moving, it does not have kinetic energy.

Reading Essentials 73 Picture This energy andpotentialenergy. compare andcontrastkinetic Make thefollowingFoldableto ● B 1. 74 Compare andContrast potential energy? on theshelveshasmost Determine Energy and Resources Which vase pe fanobjectincreases. speed of increases Kinetic asthe energy objects. forallmoving true Thisis ithas. themore kineticenergy bowling ballgoes, Thefaster the change to happenthanaslower bowling ball. Afaster bowling ballcausesmore movemight farther. orthey falldown thepinsmight ball rolls faster? More of potential (puhTENchul) energy. not have any because itisnotmoving. kineticenergy Thevasedoes thebookcase inthefigure below. vase ontop of anobjectincreases. mass of increases Kinetic asthe energy ball becauseithaslessmass. pins asfarthebowling ballwill. notmove Thevolleyball will the speed asabowling ball. How are kinetic energy andspeedrelated? How arekineticenergy Potential Energy andmassrelated? How arekineticenergy it has. potential themore energy gravitational surface anobjectis, above higher The Earth’s potential energy. called gravitational ithas. energy themore potential Themore massanobjecthas, mass. Potential alsodependson energy abovehigher thefloor. itis Avasehasmore if potential energy kinetic energy. into betransformed It will from to oneform another. orchanged, betransformed, will thepotential energy falls, thevase If above thevaseisitsheight thefloor. position of The itsposition. stored becauseof energy inanobject htwudhpe otebwigpn fthebowling What would happento thebowling pinsif hntevs sstigo h hl,hwvr ithas however, When thevaseissittingonshelf, Look atthe isnotmoving. it even if An objecthasenergy thanthebowling haslesskineticenergy The volleyball Suppose you roll avolleyballatthesame thealley down All objectsonEarth’s surface have stored potential energy, P ot e nt ial e ne r g y is the

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. increases. thematerial of increasesmaterial energy whenthethermal a temperature The of matter have more kineticenergy. thematerial’s temperature decreases. slowly, When move theparticles more temperature increases. thematerial’s When move theparticles faster, material. ina theparticles theaverage of kineticenergy measure of Temperature isa dueto motion. theirrandom particles amaterial’s Temperature isrelated of to thekineticenergy inthematerial. energy thermal same astheamountof isnotthe amaterial Thetemperature of water to increase. are alwaystheir particles moving. have Allmaterials because energy thermal motion. random inanobjectdueto their theparticles of potential energy motion. inalldirections.and moving bumpinginto each other are inconstantparticles motion, These extremely andmolecules. smallparticles—atoms to thewater energy. isthermal transferred Theenergy increase. thewater to of causes theenergy This to thewater. transferred measurement—the joule(J). unit of are measured energy usingthesame of All forms energy. orpotential kinetic energy of are types energy Most of forms infoodisdifferent inwind. fromThe energy theenergy What ischemicalenergy? relatedtotemperature? energy How isthermal energy? What isthermal Forms ofEnergy broken inyour down body to release energy. haschemicals compounds whosemoleculescanbe as sugar, chemicals are formed. isreleased chemicals when areenergy broken andnew apart this of Some potential energy. of isatype Chemical energy C in alsoincreases whentheparticles energy Thermal the Heating water onthestove causesthetemperature of What are energy? All materials isthermal madeof from is theburner energy water, When you heatapotof energy. have andwind different of forms sunlight, Food, odhsceia nryta orbd ss od such Food, Food thatyour has chemical body energy uses. he mical The r e mal ne r g e y ne is the energy storedis theenergy inchemical bonds. r g y stesmo thekineticand is thesumof This motioniscalledrandom 3. SC.A.2.3.3 ✔ FC A T energy thatituses? body getthechemical Explain

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U U S S Identify Benchmark Check Annually Assessed Reading Essentials Where doesyour What two 75 4. 76 kinetic energy. changes electricalenergyto energy, andonethat electrical energytoradiant energy, onethatchanges electrical energytothermal appliance thatchanges electricity. Identifyone devices youusethat Apply Energy and Resources Think ofthe thermal energy thatmakes foodhotter. energy thermal by microwavestransferred to thefoodandischanged into is energy radiant In amicrowave oven, one place to another. from waveselectromagnetic energy radiant which transfer are andlight also microwaves, Radiowaves, waves. travels Sunlight aselectromagnetic to Earth waves. of form radiant energy.radiant thatreaches is Thesunlight Earth before itreaches Earth. Sun’s travels energy almost150millionkmthrough space Ele What isradiantenergy? This energy isusedto produce energy.This energy electrical atoms to uranium are release splitapart energy. nuclei of the In anuclear power plant, anatom to make electricity. of energy. huge amountof inaprocess called nuclear fusionthatreleases a or fused, atoms are joinedtogether, thenuclei of In theSun, nucleus. Nuclear isreleased changes when occur energy inanatom’s anatom. thatisstoredis theenergy inthenucleus of What isnuclearenergy? What iselectricalenergy? the electrical energy the device uses. thedevice energy the electrical may thatprovide usebatteries CDplayers, such asportable Somedevices, these appliances are whenthey beingused. comesthese devices current from that ﬂows theelectric in thatruns energy Theelectrical (alightbulb). energy radiant (atoaster) or such energy asthermal energy, of types energy.around thatuseelectrical atallthedevices Look energy. useselectrical lighting Electrical current. at swre yteeeg tgt rmteSn The itgetsfrom by theSun. iswarmed theenergy Earth At the center of every atom isanucleus. every At thecenter of isusedinmany energy day. waysElectrical every Nuclear power stored plantsusethe energy inthenucleus All electrical devices change electrical energy to other energy change electrical devices All electrical ct r ical e ne r g R y adiant is the energy carried by anelectric carried is theenergy e ne r g y is energy thattravels inthe is energy N uc le ar e ne r g y

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2. 1. kinetic energy: energy: electrical energy: chemical energy: Mini Glossary 3. Column 2 on the line in front of the form of energy itmatches inColumn energy 1. of theform Column 2onthelineinfront of Write theletter theexample in thecorrect examples. with energy Match of theforms explain thedifference andkineticenergy. between potential energy Onthelines below, Read above. thekey terms anddefinitionsintheMini Glossary hn ol eaohrwyt epyurmme h ifrn om fenergy? think would beanotherway to helpyou remember thedifferent of forms What doyou inthis section. energy You were asked thedifferent of forms to highlight After You Read of potentialenergy the abilitytodowork 7. radiant energy g. the energy inanatom’s theenergy nucleus g. hottea inacupof theenergy f. abooksittingonshelf of theenergy e. rolling inaball theenergy d. energy radiant infood theenergy 7. c. alampgives off theenergy b. nuclear energy 6. chemical energy uses thatatelevision theenergy 5. a. energy thermal 4. energy electrical 3. kineticenergy 2. potential energy 1. nrya bethsbcueo t motion energy anobjecthasbecauseofits energy storedinchemicalbonds;atype energy carriedbyanelectriccurrent oun1Column 2 Column 1 games, andprojectstohelpyou learnmoreaboutenergy. Visit fl7.msscience.com to accessyourtextbook,interactive thermal energy: radiant energy: potential energy: nuclear energy: of itsposition the particlesinanobjectduetotheirrandommotion energy thattravelsintheformofwaves energy storedinthenucleusofanatom the sumofkineticandpotentialenergy the energystoredinanobjectbecause Reading Essentials Section End of 77 ● own words. then stateeachpointinyour section. Studythemainpoints, paragraph asyoureadthis Highlight themainpointineach Identify Main Ideas of energyandgiveexamples. describe thelawofconservation following Foldable.Inside, C section 78 ■ ■ ■ What You’llLearn chapter Describe 00 plants makeenergy how electricpower form how energychanges conservation ofenergy to applythelawof 6 3 Also covers: Assessed: Benchmarks—SC.A.2.3.3 AnnuallyAssessed: Energy and Resources Conservation Conservation of Energy Law of The studentidentifiesformsofenergyandexplainsthattheycanbemeasuredcompared. ● 2 SC.B.1.3.2; SC.B.1.3.4;SC.B.1.3.5;SC.B.2.3.1;SC.H.1.3.4;SC.H.1.3.5 Make the Energy andResources Energy Transformations produced during an energy transformation. produced anenergy during isalways energy Thermal by friction. energy thermal to into istransfered thebikeenergy andtransformed thebicycle are becausekinetic warmer of Theparts muscles. by his into energy thermal istransformed chemical energy biker’s The body becomes as warmer potential energy. into istransformed thisenergy someof moves upthehill, As he to thebicycle istransferred his legs ashepedals. of kineticenergy The into kineticenergy. chemical energy changes form. energy when Work isdoneandchanges occur transformations. energy to anotherare called energy changes from of onform These itischanged from to oneform anotherform. used, Any isbeing timeenergy andelectrical. radiant, thermal, The Law of Conservation ofEnergy The Law ofConservation transformations? How canyoutrackenergy Changing Forms ofEnergy today. energy Explain how you usedonekindof as the total amount of energy after theafter transformation. energy as thetotal amountof isthesame before the transformation energy total amountof the In any transformation, energy theenergy. of the form Theonlythingthatchanges is never created ordestroyed. The studentknowsthatradiation,light,andheatareformsofenergy…; The When amountainbiker transform pedalshislegs canhaveEnergy different such aschemical, forms Read toLearn Before You Read la w o f c o nse r v at io n o f e ne r g y states that energy is states thatenergy SC.B.1.3.1 Annually

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. converting a form of energy into usefulenergy. energy converting of a form is100percent transformation efficientin that noenergy means This isproduced. plus somewaste energy thermal isproduced someusefulenergy any transformation, energy in So, thatisnolongeruseful. changed into energy thermal isalways someenergy transformations, In energy wasted. soitis It doesnothelpthecarmove, longer usefulenergy. alsospreads outinto energy theair. thisthermal Someof hot. which makes theengine into energy, thermal also istransformed thechemical energy of Some in gasolineinto kineticenergy. thechemical energy anautomobile transforms engine example, For from onekindto energy another. machines transform The stays thesame. energy of Thetotal amount thatitgains. potential energy amount of thatitlosesequalsthe kineticenergy amountof The energy. is changed into potential kineticenergy The itloses kinetic energy. As itrises, iskinetic. itsenergy mostof your hand, As theballleaves occur whenyou toss aballinto theair. changes thebook’s into energy. thermal kineticenergy friction When you slideabookacross atable, decrease. andfalls. same astheballrises the thrown ballstays the of mechanical The energy energy. theobject’s potential andkinetic object isthesumof How efficient are energy changes? How efficientareenergy Using Energy Changing KineticandPotential Energy The thermal energy thatspreads outfrom energy thecarisno The thermal Many allthetimearound changes form you. Energy The figure that below transformations shows theenergy rcincncuetemcaia nryo anobjectto of Friction cancausethemechanical energy energy Kinetic me c hanical energy Potential energy Kinetic e ne r g y fan of Picture This 1. 3. 2. thermal energy? the ballistossedinair. energy andbackagainas kinetic energytopotential d. c. b. a. energy? have themostpotential whatpointdoestheball At Draw Conclusions Identify Trace halfway upintheair ball the just beforeyoucatch when itleavesyourhand highest point when itreachesits Reading Essentials the changesfrom What iswaste 79 4. 5. 80 through theairinaroom? thermal energymove energy. ways peopleuseradiant Summarize Explain Energy and Resources How does Name three are eaten by humans andotherorganismsasfood. thesecompounds Someof into chemicalsunlight compounds. in Plants usephotosynthesis to energy change theradiant your body moves. Your of muscles contract andapart shape. reactions take place moleculesto andcausecertain change Chemical happensinmuscle This cells. inside your body. bet,sc stebae fafn move. afan, such as thebladesof objects, byconvert into making kineticenergy energy electrical motors Electric to orwater. heatbuildings energy thermal Someischanged into to provide light. energy into radiant ischanged energy thiselectrical Someof the United States. treat disease. thebody andsohelpthem theinsideof make imagesof Theserays helpdoctors usedinmedicine. energy radiant rays X andgammarays are of forms energy. electrical from theSun Radiantenergy canbeconverted into to see. aswaves. energy which transfers radiation, canalsomove energy by Thermal place to acooler place. move inaliquidorgas particles fromwhen awarmer as It canmove by convection, by each colliding other. with energy transfer inamaterial happens whentheparticles which It canmove by conduction, move inthree ways. can energy Thermal colder andthenspreads material out. and keep you warm. isusedto heatbuildings energy Thermal flows inawire. current whenanelectrical into energy thermal transformed is energy Electrical into energy. thermal transformed is chemical energy When somethingburns, energy. How is chemical energy used? How ischemicalenergy How is electrical energy used? How iselectricalenergy used? How isradiantenergy move? energy How doesthermal used? energy How isthermal The energy stored in food originally camefrom stored theSun.The energy infoodoriginally into kineticenergy canbetransformed Chemical energy A huge amount of electrical energy is used every day in isusedevery energy electrical A huge amountof that allowsVisible you energy provides theradiant light moves energy fromThermal to material a awarmer into thermal canbetransformed energy of All forms

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. cause disorder to increase. events thatoccur intheuniverse always In fact, spreads. thefoodcoloring becomes more disordered asit water, of foodcoloring isplaced into aglass whena drop of example, For matter alsobecomes more disorganized anddisordered. intheuniversedisorganized energy isalways increasing. meansthatthetotal This amountof disorganized energy. becomes someorganized energy occurs, transformation spreads outinto theairandisnotusedto helpmove thecar. heatproduced extra The by acarengine is notneeded. anditspreads outto where it can’t beusedisdisorganized, that Energy isorganized energy. inabattery energy electrical The organized way inacertain anddoesnotspread out. thatis that cannotbeused?Useful isenergy energy How different from isusefulenergy energy always decreases. to agenerator. turn similar way—they useenergy work ina like theoneinfigure below, power plants, All energy. into electrical kineticenergy thattransforms device A rotatesturbine ashaftinthegenerator. The The steam theturbine. pushesonthebladesandturns fanbladesthatare closetogether. a machine thathasasetof Steam from theboilingwater through aturbine, rushes water. to gasisburned boil ornatural oil, coal, fuel power plants, In fossil from? It must bemadeallthetimeby power plants. Why doesdisorder always increase? andDisorganized Energy Organized Energy Generating ElectricalEnergy Just becomes more asenergy disorganized over time, Whenever anenergy Useful isorganized energy. energy usefulenergy theamountof transformations, In energy outletcomeWhere inanelectrical energy doestheelectrical g e ne r at o r is a Picture This 6. 7. Define energy isbeingreleased. figure wheredisorganized Mark into electricalenergy? transforms kineticenergy Reading Essentials the placeon What device 81 After You Read Mini Glossary generator: a device that transforms kinetic energy into mechanical energy: the sum of an object’s potential and electrical energy kinetic energy law of conservation of energy: states that energy is never created or destroyed

1. Review the terms and their deﬁnitions in the Mini Glossary. Explain how a generator makes electrical energy.

2. Fill in the blanks to tell what type of energy is being transformed as a biker rides a bicycle.

A biker eats food. Food contains

energy.

When a biker’s muscles move, the energy in food is turned into

energy.

The biker’s working muscles make The biker’s muscles turn the him hot. Some of the energy in his pedals on the bike. This makes the muscles is turned into bike move. So his muscle energy is transformed into energy. energy in the bike. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive games, Section and projects to help you learn more about energy transformations.

82 Energy and Energy Resources chapter Energy and Energy Resources 0063 section ●3 Sources of Energy Benchmarks—SC.A.2.3.3 Annually Assessed: The student knows that radiation, light, and heat are forms of energy …; SC.H.3.3.7 Annually Assessed: The student knows the positive and negative consequences of human action on the Earth’s systems. Also covers: SC.B.2.3.2; SC.G.2.3.1; SC.H.1.3.4; SC.H.1.3.7; SC.H.3.3.7

Before You Read What You’ll Learn ■ what renewable, You must plug in most appliances before they will work. nonrenewable, and Where does the energy in an electrical outlet come from? alternative resources are ■ about the advantages and disadvantages of using different energy sources

Read to Learn Identify Details As you Energy Only Changes Form read this section, highlight the text each time you read about Energy is used every day to provide light and heat to an energy source. homes, schools, and workplaces. The law of conservation of energy states that energy cannot be created or destroyed. It only can change form. If a car or refrigerator cannot create the energy they use, where does the energy come from? Energy Resources Energy must come from the natural world. The surface of Earth gets energy from two sources–the Sun and radioactive atoms in Earth’s interior, as shown in the ﬁgure below. Earth gets far more energy from the Sun than is made in Earth’s interior. Almost all the energy you use today can be traced to the Sun. Even the gasoline used to power a car can ●D Organize Information be traced to the Sun. Make the following Foldable to organize information about the fossil fuels, nuclear energy, Surface hydroelectric energy, and of Earth alternative sources of energy.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Radiant energy Thermal energy from from radioactive the Sun atoms

Reading Essentials 83 contrast energysources. notebook papertocompareand Use threequarter-sheetsof ● Picture This E 1. 84 Compare andContrast molecules? molecules intocoal things changedtheplant Identify Nonrenewable Energy and Resources Resources Inexhaustible Resources What three Renewable Resources Radiant energy the fossilfuelsare burned. stored Chemicalenergy infossilfuelsisreleased when fuel. heatandpressure changed thesemoleculesinto fossil time, Over isstored chemical The energy inmolecules. energy. from into chemical sunlight energy theradiant transformed ancientplants photosynthesis (fohtoh SIHNthuh sus), Through plantsthatonce lived onland. remains of inasimilarway. Coal wasformed gas. pressure slowly theseorganismsinto turned oilandnatural Heat and years ago. that lived inEarth’s oceans of millions microscopic organisms gas were madefrom theremains of that isusedupmuch faster thanitcanbereplaced. are burned might causeEarth’sare might burned climate to warm. dioxide carbon The whenfossilfuels gasthatforms rain. illnessesandacid Thesepollutantscauserespiratory fuels. airpollutantsare produced by fossil burning of kilograms Each year billionsof compounds that causepollution. A resources. Fossil fuelsare nonrenewable used. is decreasing asit keep will fossilfuelsonEarth means thattheamountof This coal thatisburned. gasoline andeach lumpof drop of years to replace each It takes millionsof cars andtrucks. to power to heathomes, fuels are usedto make electricity, What aresomedisadvantagesof fossil fuels? How arefossilfuelsused? Fossil Fuels ssoni h grsblw coal wasmadefrom the As intheﬁgures shown below, Burning fossil fuels for energy produces fossilfuelsforenergy Burning chemical Fossil you usecomes theenergy from fossilfuels. Most of F ossil fue oslFe Formation Fossil Fuel ls no Pressure r ol i,adntrlgs Oilandnatural gas. andnatural oil, are coal, Time Heat nr e ne wab le r esour c e Coal mine is an energy sourceis anenergy

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. released into the environment for alongtime. be carefully will andsafelystored sonoradioactivity Thismeansthatnuclear waste must be years. thousands of innuclear remainmaterials waste radioactive will formany the Someof and canbedangerous to things. living Another disadvantage isthatnuclear waste isradioactive It comes from Earth’s crust. a nonrenewable resource. itproduces only1m To dothis, power. with power to supply600,000homes plantmakes energy enough nuclear typical a In oneyear, produce almostnoairpollution. Nuclear power plantsalso fossilfuelslastlonger. the supplyof figure below shows thisprocess. The Thegenerator produces electricity. generator. electric by heatingwater toelectricity produce steam thatspinsan isusedto make energy This nuclear energy. amounts of release they huge When thesenuclei break apart, atoms. uranium Theanswer isinthenucleiso much of energy? gas? What could supply asalmost3millionliters of energy What arethedisadvantagesofnuclear energy? What aretheadvantagesofnuclearenergy? Nuclear Energy One disadvantage of nuclear energy is that uranium is isthaturanium nuclear energy One disadvantage of helpsmake by usingnuclear energy electricity Generating fuelthatreleases asmuch Can you 1kgof imagine 1. Nuclearenerg o f a t o m s y Electrical EnergyfromNuclear 2. Thermalenergy of water 3. Kineticenergy o f ste 3 am fwaste. of 4. Kineticenerg o f t u r b in e Picture This Gener 3. 2. y nuclear powerplant? the turbinehaveina energy doesthesteamand Determine Identify nuclear energy? two disadvantagesof a t or 5. Electricalenerg Reading Essentials What typeof What are y 85 Picture This 1. Potentialenergy 4. 86 ofwater the dam? have asitflowsthrough energy doesthewater Identify Energy and Resources What typeof 2. Kineticenergy ofwater disasters could causetheradioactive to material leak. Earthquakes andothernatural disasters. other natural It alsohasto besafefrom earthquakes and water supplies. It cannotbenearunderground has to bechosen carefully. them Theplace to bury containers arefarunderground. buried the Then thatisputinprotectivematerial containers. renewable source of energy. A A energy. renewable source of Hydroelectricity isthelargest comes fromenergy water. theworld’s electrical About 20percent of figure below. Thisprocess isshown inthe way iscalledhydroelectricity. madethis Energy energy. into electrical can betransformed and buildfishladdersto helpfishgoaround otherdams. There are plansto remove somedams dams. places becauseof Many salmoncannotreach these hatched to lay theireggs. Salmonreturn to thespotupriver where were they Northwest. River damshave causedproblems forsalmoninthe water. someanimalsthatlive inthe Dams upsetthelifecycle of hydroelectricity doeshave amajordisadvantage. production of the However, electricity. over someothersources of hydroelectric power plantscanmake electricity. flow, As longasrivers sourceenergy thatisreplaced continually. How cannuclearwaste bestored? Hydroelectricity One way to store nuclear waste isto sealitinaceramic The potential energy of water trapped behindadam water trapped of The potential energy yreetiiymksltl olto.Thisisanadvantage Hydroelectricity makes littlepollution. 3. Kineticenergy ofturbine 4. Electricalenergy outofgenerator r e ne wab le r esour c Long-distance power lines e is an

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. They alsoareThey usedonthe Photovoltaics are usedincalculators andsatellites. energy. directly into electrical energy radiant that transforms (foh toh vohl TAY ihk)collec buildings? Thesearebuildings? collectors forsolarenergy. housesor ever seenlargerectangular panelsontheroofs of Alternative resources are beingresearched. disadvantages theenvironment that can affect andhumans. other energy sourcesother energy to make electricity. or becheaper to usesolarenergy itmight Then, fossil fuels. become itmight more expensive to ﬁndandmine decreases, fossilfuels asthesupplyof However, use thanfossilfuels. ismore Onereason expensive isthatsolarenergy to energy. usedintheUnitedthe energy States comes directly from solar But lessthan0.1percent of inoneyear. used by thecountry energy States inoneday ismore thanthetotal amountof thathits theUnited solarenergy Theamountof humans. Photovoltaic Thermal Collector How istheSun’s collected? energy r Solar Energy r SourcesofEnergy Alternative solar energy, wind, and geothermal energy. andgeothermal wind, solar energy, Alterative resources include toharmful theenvironment. used forwashingandbathing. ahouse to through pumped be hotwater The can The water canbeheated to about 70°C. collectorthermal usestheSun’s energy radiant to heatwater. The thanany more energy othercolor. radiant absorbs Black a blacksurface theSun’s to absorb energy. radiant collector A thermal uses were they collectors. thermal them, esour esour w ye fcletr aei h u’ as Have you collectors take intheSun’s rays. Two of types An The Sun isaninexhaustible resource. Each has There are many ways to make energy. electrical c c e es is an energy sourceis anenergy thatcannotbeusedupby are new sources of energy thatare saferandless energy are newsources of fthepanel If fthepanelshadpipescoming outof If a opps it isaphotovoltaic has nopipes, International SpaceInternational Station o.Aphotovoltaic isadevice tor. poieha.It canalsobe heat. provide A inexhaust lt e r nat i v e ib . le 5. resource istheSun? Identify Reading Essentials What typeof 87 Picture This 6. 7. 88 reservoirs turnwaterinto? the magmaingeothermic Determine Circle house. panels ontheroofof Energy and Resources the photovoltaic What does enough to thesurfaceenough to andgeysers. make hotsprings reservoirs are Geothermal sometimesclose reservoirs. Theseare calledgeothermal pressure andpockets. incracks Thehot water underhigh and steam canbetrapped steam. heatsthewater anditcanbecome The magma surface. inEarth’s andopenings through thecracks the magma Rainwater andwater from melted snow to canseepdown gets closeto thesurface andheatstherock around it. magma In otherplaces, the surface whenavolcano erupts. Magma reaches the surface inEarth’s through cracks crust. upcloseto Magma rises rock iscalledmagma. or molten, Melted, to thetemperature meltrock. ishotenough Earth, At someplaces deepwithin into energy. thermal energy nuclear Thistransforms radioactive decay. atoms insideEarth ismadewhenunstable energy geothermal Some energy. thetemperature could beover 900°C. 100km, depth of At a the temperature to would boilwater. enough bewarm After goingonlyabout3km, temperature would increase. the As you went deeperanddeeper, km below thesurface. What are geothermal reservoirs? What aregeothermal Energy Geothermal In some places, magma is very closeto isvery Earth’s magma surface. In someplaces, iscalledgeothermal inside Earth The heatgenerated about6,400 Earth, youImagine could goto thecenter of John Keating/PhotoResearchers

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. heat pump into thebuilding. heatfromwater absorbs theground andreleases itfrom the thecool Then, the airiscooler thantheground below. In thewinter, backtopumped heat. thebuildingto absorb The water cools andthenis through thecooler ground. water Aheatpumpsendswarm from thebuilding below. bybuildings usingaheatpump. This constant temperature canbeusedto heator cool to 20°C. several meters atabout10° ground atadepthof the western United States. such asin reservoirs aregeothermal closeto Earth’s surface, But power geothermal plantscanbebuiltonlywhere power Geothermal isaninexhaustible resource. electricity. by power geothermal plantsto make electricity. Hot water isused andsteam from energy geothermal deep. places where thereservoirs are lessthanseveral kilometers How areheatpumpsused? powerHow isgeothermal made? t s a its wa reserv a H u u During the summer, the air is warmer thantheground theairiswarmer thesummer, During the heathelpskeepGeothermal thetemperature of The ﬁgure above shows how reservoirs geothermal make Wells to reach canbedrilled reservoirs geothermal in o p g rns t rf t w i eothermal p a e tothe ce whereit y a o o through ter fr ir f ste o a rces o m m . Geothermal PowerPlant electric c t The ste u o r nnecte b ine th a g m t enerator d a t t is u o

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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. energy when you when recycleenergy aluminum cansandglass. You alsohelpconserve andtherefore lessenergy. and oil, would they uselessgas less orwere mademore efficient, carswere used If orinto your house. from leakingoutof keep heat Thiswill itis hotorcold when outside. tightly Keep closed doorsandwindows them to conserve energy. appliances like whenyou televisions are notusing off turn energy.called conserving Using is lessenergy needto people uselessenergy. longer, fossilfuelslast To make thesupplyof and othermaterials. Oiland coal canbeusedto make plastics provide energy. spins ismadewhenwind energy Electrical energy. into electrical thewind of kinetic energy the transform like theonesinfigure below, windmills, Conserving Energy Conserving Wind sometimes are killedby windmills. studieshave thatbirds shown Also, windmills. place alotof landonwhich to You alsoneedalargearea of make noise. do But windmills producewindmills almostnopollution. These which makes electricity. is connected to agenerator, o a aemnyb osrigeeg.YouYou should cansave energy. by money conserving are to They burned Fossil fuelsare avaluableresource. Modern energy. Wind isanotherinexhaustible supplyof h rple.T the propeller. he propeller Picture This 12. 13. conserve energy? another wayyoucan Infer Describe mountains? between hillsor mountains insteadof figure areplacedontopof the windmillsshownin Reading Essentials Why doyouthink What is 91 3. 2. 1. fossil fuel: alternative resources: Mini Glossary inexhaustible resource: 92 did this help you learn about energy sources?did thishelpyou about energy learn How You were asked thetext to each timeyou highlight source. read aboutanenergy asyouchart can. andinexhaustible resources inthe nonrenewable, renewable, Write asmany examples of between arenewable resource andanonrenewable resource? What isthedifference Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section energy sources used upbyhumans End of Energy and Resources coal, oil,andnaturalgas eeal eore ornwbeRsucsInexhaustibleResources NonrenewableResources Renewable Resources new renewableorinexhaustible an energysourcethatcannotbe and projectstohelpyoulearnmore aboutsourcesofenergy. Visit fl7.msscience.com renewable resource: nonrenewable resource: much fasterthanitcanbereplaced continually to accessyourtextbook,interactive games, an energysourcethatisreplaced an energysourcethatisusedup

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chapter Waves, Sound, and Light 73 section ●1 Waves Benchmarks—SC.A.2.3.1: The student describes and compares the properties of particles and waves; SC.B.1.3.6 Annually Assessed: The student knows the properties of waves; S.C.C.1.3.2 Annually Assessed: The student knows that vibrations in materials set up wave disturbances that spread away from the source. Also covers: SC.H.1.3.4; SC.H.1.3.5; SC.H.2.3.1 Before You Read What You’ll Learn ■ how waves carry energy Have you ever seen a crowd of people do a wave at a ■ the differences among sporting event? Describe what people doing a wave looks like. types of waves ■ the properties of waves ■ what happens during the reﬂection, refraction, and diffraction of waves

Read to Learn Locate Information What are waves? Underline every heading in this section that asks a question. When you ﬂoat in the ocean, waves move past you. The Then, use a different color to waves move you up and down. Waves can be so strong highlight the answers to those they knock you over or they gently rock you. You know questions. there are waves in the water because you can see them and feel them. Did you know there are other types of waves? Sound waves make it possible for you to hear. Light waves make it possible for you to see. Other waves carry signals to radios and televisions. Waves even cause the damage from earthquakes. What do waves transfer? A wave is a disturbance that moves through matter or through empty space. Waves do not transfer matter. They transfer energy from one place to another. ●A Build Vocabulary Imagine throwing a stone in a pond. When the stone hits Make the Foldable shown below. Use it to deﬁne some terms in the water, it causes a disturbance. It makes waves. The waves this section. look like they carry water with them as they move. But that is not what really happens. When the stone hits the water, the energy is transferred to water molecules nearby. These wave types of water molecules move energy to other water molecules. The waves wavelength

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright energy is passed from water molecule to water molecule. You frequency see this movement of energy as the waves spread out farther amplitude law of reflection and farther. The waves move away, transferring energy. But, refraction the water molecules barely move from their places. diffraction

Reading Essentials 93 Types of Waves Waves usually are produced by an object moving back and forth, or vibrating. Waves carry the energy of the vibrating object. This energy can spread out from the vibrating object in different types of waves. One type of 1. Identify What do waves wave is a mechanical wave. Mechanical waves can travel only carry? in matter and not through space. Another type of wave, an electromagnetic wave, can travel through matter or through empty space. What are transverse waves? What happens if you tie a rope to a door handle and shake the rope up and down? You have made a mechanical wave called a transverse wave, like the one in the ﬁgure below. A transverse wave causes the particles in matter to move back and forth at right angles to the direction that the wave is traveling.

Crest Direction wave moves

Picture This 2. Draw and Label Draw a 90-degree angle on the ﬁgure to show that the rope Direction rope moves moves at right angles to the Trough direction the wave moves. Label the angle.

Look at the transverse wave in the ﬁgure above. The shorter arrows show the direction the rope is moving. The rope is moving up and down. The longer arrow shows the direction the wave is moving. The wave is moving forward. The arrows for the rope and the wave are at right angles to each other. This shows that the particles in the rope are moving at right angles to the direction the wave is traveling. Crests and Troughs The points where the wave is highest are called crests. The points where the wave is lowest are Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright called troughs. A series of crests and troughs forms a transverse wave. The crests and troughs move along the rope. But, the particles in the rope move only up and down.

94 Waves, Sound, and Light What are compressional waves? Imagine you and a friend are each holding an end of a spring. When you pull and push on your end of the spring, you make another kind of mechanical wave. It is called a compressional wave. A compressional wave makes the particles in matter move back and forth in the same direction the wave is traveling. The ﬁgure below shows a compressional wave moving along a spring. The places where the coils are squeezed together are called compressions. The places where the coils are spread apart are called rarefactions (rare FAK shunz). The repeating compressions and rarefactions make a compressional wave. The compressions and rarefactions travel along the spring. But the coils move only back and forth.

Picture This 3. Identify Highlight the rarefaction in the wave. Use a different color to highlight the compression in the wave.

What are electromagnetic waves? Light, radio waves, and X rays are examples of electromagnetic waves. Just like waves on a rope, they are transverse waves. However, electromagnetic waves have electric and magnetic parts. These parts vibrate up and down at right angles to the direction the wave travels. 4. Classify What kind of Properties of Waves wave is an electromagnetic wave? The properties of waves depend on the vibrations that produce them. The faster you shake the end of a rope up

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright and down, the closer the crests and troughs will be. If you shake the end of a rope by moving it up and down a greater distance, the crests will become higher, and the troughs will become deeper. You changed the properties of the waves by changing the movement of the rope.

Reading Essentials 95 Wavelength Wavelength

Wavelength Wavelength

Picture This What is the wavelength of a wave? 5. Identify Highlight one Wavelength is the distance between any point on a wave wavelength of the and the nearest point just like it. The figure above on the transverse wave in the left shows the wavelengths of a transverse wave. It is the figure. Then highlight one wavelength of the distance from one crest to the next crest or from one trough compressional wave.The to the next trough. The figure above on the right shows the student wavelengths of a compressional wave. A wavelength of a compressional wave is the distance between two adjoining compressions or rarefactions. Wavelength is measured in units of meters (m). What is the frequency of a wave? The frequency of a wave is the number of wavelengths that pass by a point each second. The SI unit for frequency is hertz (Hz). One hertz equals one vibration per second or one wavelength passing a point in one second. If five wavelengths pass by a point in one second, the frequency of the wave would be 5 Hz. The unit Hz is the same as 6. Evaluate What is the the unit 1/s. frequency of a wave where 20 crests pass by you each What is amplitude and how is it measured on second? a transverse wave? Suppose you shake the end of a rope by moving your hand up and down a large distance. You make a transverse wave with high crests and deep troughs. The wave you have made has a large amplitude. The amplitude of a wave is the greatest distance that matter moves as the wave passes. The amplitude of a transverse wave is the distance from the top of the crest or the bottom of a trough to the rest position of the material. You can see this in the figure at Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright the top of the next page. As the distance between crests and troughs increases, the amplitude of a transverse wave becomes larger.

96 Waves, Sound, and Light Amplitude of a Transverse Wave Crest Rest

Picture This 7. Draw and Label Draw and label a transverse wave with a small amplitude in one box. Draw and label a Trough transverse wave with a larger amplitude in the other box. How is amplitude measured on a compressional wave? The amplitude of a compressional wave depends on how close together the material is at the compressions and rarefactions. Compressional waves with greater amplitude have compressions that are closer together. Their rarefactions are farther apart. Think about a spring. When you squeeze some parts of the spring together tightly, other parts of the spring spread apart more. How are amplitude and energy of a wave related? The vibrations that produce a wave transfer energy to the wave. The more energy a wave carries, the larger its amplitude. Think about making a transverse wave on a rope again. If you move your hand up very high then down very low, you transfer a lot of energy to the rope. You make a wave with a large amplitude. If you move your hand up and down only a little, you transfer a small amount of energy. You make a wave with a small amplitude. What are seismic waves? Waves that are formed in Earth’s crust during an earthquake are called seismic waves. Some of these waves are compressional. Others are transverse. The seismic waves that cause the most damage to buildings are a kind of rolling wave. These rolling waves are a combination of compressional and transverse waves. The larger the Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright amplitude, the more energy these waves carry. Seismic waves with large amplitudes carry a great amount of energy. The larger the amplitude of a seismic wave, the more damage it causes as it moves along Earth’s surface.

Reading Essentials 97 How fast do waves travel? The wavelength, frequency, and speed of a wave are related. The faster a wave travels, the more wavelengths pass you by each second. You can calculate the wavelength of a wave if the wave speed and frequency of the wave are known. Applying Math Use the equation below. 8. Solve One-Step wave speed (in m/s) Equations Calculate the wavelength (in m) wavelength of a wave that frequency (in Hz) has a wave speed of 340 v m/s and a frequency of 34 f Hz. Show your work. In this equation, v is the symbol for wave speed, and f is the symbol for frequency. The Greek letter lambda, , is the symbol for wavelength. Waves Can Change Direction Waves do not always travel in a straight line. You see your reflection in the mirror because the mirror makes light waves change direction. Waves can bounce off a surface, or reflect. They can change direction, or refract. Waves also can bend around an object, or diffract. How do waves reflect? When waves reflect off a surface, they always obey the law of reflection. A line that makes a 90 degree angle with a surface is called the normal to the surface. The law of reflection states that the angle the incoming wave makes with the normal equals the angle the outgoing wave makes with the normal. The figure below shows the normal and the two angles made when a flashlight reflects off a surface.

Picture This 9. Analyze Use a protractor to measure each angle in Normal the ﬁgure. Are they equal? Write down the angle measure of each angle. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

98 Waves, Sound, and Light What makes a wave change direction? The speed of a wave depends on the properties of the material through which it travels. For example, a light wave travels faster through air than through water. The ﬁgure below shows a light wave that travels through air and then through water. The wave does not travel in a straight line. It changes direction. When the wave moves from the air to the water, it slows down. Waves change direction when they slow down or when they speed up. When a light wave changes speed, it bends. Refraction is the change in direction of a wave when it changes its speed as it travels from one material to another.

Picture This 10. Identify Which material in the ﬁgure does the light wave move through faster—air or water?

What causes diffraction? When waves hit an object they cannot go through, the waves bend around the object. Diffraction is the bending of waves around an object. Waves can diffract a small amount or a large amount. If the object is much larger than the

F wavelength, the wave diffracts only a small amount. If the T OC A U C Annually Assessed

S wavelength is larger than the object, the wave diffracts a F Benchmark Check greater amount. As the wavelength gets larger compared to the object, the amount of diffraction increases. SC.B.1.3.6 ✔ 11. Determine How do waves compare to particles? What happens to a wave Waves are different from particles of matter. Particles have when it hits an object it mass and take up space. Particles have a positive or negative can’t pass through?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright electric charge. Waves do not have any of these properties. However, waves and particles are both in constant motion. Moving particles and waves both transfer energy from one place to another.

Reading Essentials 99 After You Read Mini Glossary amplitude: the greatest distance that matters move as a refraction: the change in direction of a wave when it changes wave passes. its speed as it travels from one material to another diffraction: the bending of waves around an object wave: a disturbance that moves through matter or through frequency: the number of wavelengths that pass by a point empty space; carries energy, not matter in one second wavelength: the distance between one point on a wave and law of reﬂection: the angle the incoming wave makes with the nearest point that is moving with the same speed the normal equals the angle the outgoing wave makes and direction with the normal

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence that describes how frequency relates to wavelength.

2. Complete the table below to help you review what you have read about waves.

Transverse Waves Compressional Waves

Motion of Particles

Wavelength the distance between two crests or two troughs that are next to each other

Frequency

Amplitude depends on how close together the material is at the compression and rarefaction Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about waves.

100 Waves, Sound, and Light chapter Waves, Sound, and Light 73 section ●2 Sound Waves Benchmarks—SC.B.1.3.6 Annually Assessed: The student knows the properties of waves; that each wave consists of a number of crests and troughs; and the effects of different media on waves; SC.C.1.3.2 Annually Assessed: The student knows that vibrations in materials set up wave disturbances that spread away from the source. Also covers: SC.H.1.3.5; SC.H.3.3.6; SC.H.3.3.7 Before You Read What You’ll Learn ■ how sound waves are Think about the sounds you hear everyday. On the lines produced below, write at least three words that describe sounds. ■ how sound waves travel through matter ■ how humans hear sound

Read to Learn Study Coach Create a Quiz After you have Making Sound Waves read this section, create a ﬁve question quiz based on what you How does hitting the head of a drum produce sound have learned. After you have waves? When you hit the head of a drum, you make it written the quiz questions, be vibrate. The vibrations transfer energy to air particles near sure to answer them. the drum head. This produces sound waves in the air. When the sound waves reach your ear, you hear the drum. Every sound you hear is made by something vibrating. For example, when you talk, tissues in your throat vibrate in different ways. These vibrations form sounds. What type of wave are sound waves? The sound waves produced when an object vibrates are compressional waves. When you hit the head of a drum, it vibrates. The air particles near the drum start to vibrate. When the drum head moves outward, it compresses the air particles nearby. The compressed particles form the compression in a ●B Find Main Ideas Make compressional wave. When the drum head moves inward, it the following Foldable to help causes rarefactions in the nearby air particles. The inward and you identify the main ideas outward movement of the drum head makes the same pattern about sound.

of compressions and rarefactions in the air particles. The Intensity: Decibel Scale particles of air vibrate with the same frequency as the and Loudness:

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright frequency of vibrations in the drum head. The energy carried by a sound wave is transferred by particles bumping into other particles. This means that Frequency: Pitch: sound waves can only travel through matter. They cannot travel through empty space.

Reading Essentials 101 The Speed of Sound Sound waves travel at different speeds through different materials. Sound waves travel faster through solids and liquids. They travel slower through gases. The table below shows the speeds of sound waves traveling through a solid, a liquid, and a gas. Sound waves also travel faster in warmer materials than they do in cooler ones. Picture This Speed of Sound 1. Identify What material Material Speed (m/s) listed in the table does sound waves travel through Glass 5,640 the fastest? Water (25°C) 1,493 Air (20°C) 343 The Loudness of Sound What makes one sound loud and another soft? The amount of energy carried by the sound waves makes the sound loud or soft. Loud sounds have more energy than soft sounds. What is the intensity of a sound? The intensity of a sound is the amount of energy a wave carries past a unit area each second. The intensity of a sound decreases with distance. When you clap your hands, sound waves spread out as they move away from you. The energy the waves carry also spreads out. Someone standing close to you hears an intense sound. Someone standing farther away hears a less intense 2. Summarize Explain sound. The intensity of sound waves is related to the why a sound becomes less amplitude. Sound waves with greater amplitude also have intense the farther you are greater intensity. from the object making the sound. How is the intensity of a sound measured? The intensity of a sound wave is measured in units called decibels (dB). The softest sound a person can hear has an intensity of 0 dB. Normal speech has an intensity of about 50 dB. Sounds with intensities of around 120 dB or higher are painful to people. Loudness is how humans hear the intensity of sound waves. Each increase of 10 dB in intensity multiplies the

energy of the sound wave ten times. To most people, a Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright sound that has an intensity 10 dB higher than another sound is twice as loud. An intensity increase of 20 dB is an increase in energy of 100 times. The loudness of the sound increases by about four times.

102 Waves, Sound, and Light Frequency and Pitch Frequency The frequency of sound waves depends on the frequency of the vibrations that produce the sound. Recall that wave frequency is the number of vibrations per second. Frequency is measured in hertz (Hz). If you play an instrument or sing, you know about notes and the musical scale. On the musical scale, the note C has a frequency of 262 Hz. The note E has a frequency of 330 Hz. People usually are able to hear sounds with frequencies between about 20 Hz and 20,000 Hz. Pitch How can you describe the frequency of a sound? Pitch describes how humans hear the frequency of a sound. Sounds with low frequencies have low pitch. Sounds with high frequencies have high pitch. The sounds from a tuba have a low pitch. The sounds from a flute have a high pitch. 3. Explain What kind of Hearing and the Ear frequency does a sound with a low pitch have? Your ear is an organ that allows you to hear many different sounds. There is more to your ear than the part you can see. The ear is divided into three parts––the outer ear, the middle ear, and the inner ear. The Outer Ear The outer ear collects sound waves. It is made up of the part you can see and also the ear canal. The part you see is shaped somewhat like a funnel. This shape helps collect the sound waves and send them into the ear canal. The Middle Ear The middle ear makes sounds louder. It is made of the eardrum and three tiny bones. The bones are called the hammer, the anvil, and the stirrup. When sound waves move down the ear canal, they press against the eardrum and make it vibrate. The vibrations move from the 4. Think Critically Think eardrum to the three small bones. These bones make the about how fast sound vibrations stronger. moves through different materials. What is the The Inner Ear The inner ear contains the cochlea advantage of the cochlea being filled with fluid (KO klee uh). The cochlea is shaped like a small snail. instead of air? It is filled with fluid and lined with tiny hair-like cells. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Vibrations move from the stirrup bone in the middle ear to the hair cells in the cochlea. The movement of the hair cells produces signals that travel to the brain. The brain understands these signals as sounds.

Reading Essentials 103 How do the parts work together? The ﬁgure below shows the different parts of the ear. The outer ear is the sound collector. The middle ear is the sound ampliﬁer. It makes the sounds louder. The inner ear is the sound interpreter. The inner ear sends signals to the brain so you hear sounds.

Outer Ear

Middle Ear Inner Ear Hammer Anvil Picture This 5. Interpret Scientiﬁc Illustrations Highlight the path a sound wave takes through the ear in the diagram.

Cochlea Ear canal Eardrum Stirrup

The Reflection of Sound Have you ever heard an echo? Echoes are sounds reflected off surfaces. A reverberation (ree ver buh RAY shun) is a repeated echo. Concert halls and movie theaters try to lessen reverberation. They have soft materials on the ceilings and walls to keep sound from reverberating too much. The soft materials absorb the energy of the sound waves. Echolocation The reflection of sound can be used to locate objects. Echolocation is the process of finding objects by bouncing sounds off them. Bats, dolphins, and other animals give off high-frequency sound waves. The waves 6. Explain How do bats reflect off of objects and back to the animal. The animal and some other animals can locate and identify objects from the reflected waves. locate objects? Medicine Doctors also use reflected sound waves in medicine. Ultrasonic waves can be reflected off of body Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright parts. Computers use the waves to produce pictures of the inside of the body.

104 Waves, Sound, and Light After You Read Mini Glossary intensity: the amount of energy a sound wave carries past a loudness: how humans hear the intensity of a sound certain area each second pitch: describes how humans hear the frequency of a sound

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence using one of the terms above.

2. Complete the ﬂow chart to show the path taken by a sound wave from the time it enters your ear until you hear the sound.

Outer ear Hammer

Brain

3. How can you use the quiz questions you created to help you study for a test about sound waves? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Visit ﬂ7.msscience.com to access your textbook, interactive End of games, and projects to help you learn more about sound Section waves. Reading Essentials 105 chapter Waves, Sound, and Light 73 section ●3 Light Benchmarks—SC.A.2.3.3 Annually Assessed: The student knows that radiation, light, and heat are forms of energy used to cook food, treat diseases, and provide energy; SC.B.1.3.3 Annually Assessed: The student knows the various forms in which energy comes to Earth from the Sun. Also covers: SC.B.1.3.6; SC.H.1.3.2; SC.H.1.3.3; SC.H.1.3.5; SC.H.1.3.6; SC.H.3.3.5; SC.H.3.3.6

What You’ll Learn Before You Read ■ the properties of light waves What would life be like without light? On the lines below, ■ about the electro- describe two things for which you need light. magnetic spectrum ■ how humans see

Read to Learn Restate the Main Point Highlight the main point in each Waves in Empty Space paragraph. Restate the main point in your own words. You see the Moon when you look up in the sky because of light waves. Light is an electromagnetic wave that can be seen by the human eye. Like sound waves and waves in water, light waves can travel through matter. But, light waves can do something these other waves can’t. Light waves can travel through space that contains almost no matter. Electromagnetic waves are waves that can travel through matter and through empty space. How fast can light travel? Have you ever seen a movie in which spaceships travel faster than the speed of light? That is impossible, because nothing travels faster than the speed of light. In empty space, light travels at about 300,000 km/s. That means that light from the Sun can travel 150 million km to Earth in only eight and a half minutes. Light travels fastest through empty space and slowest through solids. Matter has atoms 1. Explain Why does light and molecules in the material that slow down light. travel slowest through solids? How long is a wavelength of light? Wavelengths of light are so short they are usually Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright measured in a unit called the nanometer (nm). One nanometer is extremely small. It is one billionth of a meter. For example, green light has a wavelength of about 500 nm, or 500 billionths of a meter.

106 Waves, Sound, and Light Wavelength Picture This 2. Interpret Scientiﬁc Magnetic field Illustrations On the ﬁgure, highlight and label a wavelength other than the one labeled.

Direction Electric field of travel

Properties of Light Waves Light waves, like all electromagnetic waves, are transverse waves. Remember the transverse wave on a rope? The transverse wave made the rope move at right angles to the direction the wave moved. Electromagnetic waves also make matter move at right angles to the direction the wave is moving. An electromagnetic wave has an electric part and a magnetic part. Both parts are called fields. They are shown in the diagram of a light wave in the figure above. Both fields vibrate at right angles to the direction the wave moves. The frequency of an electromagnetic wave is the number of times the electric and magnetic fields vibrate in one second. The wavelength of an electromagnetic wave is the distance between the crests or troughs of the vibrating electric or magnetic fields. How is the intensity of a light wave measured? The intensity of waves is a measure of the amount of energy that the waves carry. The intensity of light waves tells about the brightness of a light. A dim light has lower intensity. Its waves carry less energy. A bright light has higher intensity. Its waves carry more energy. As you move away from a light source, the energy spreads out and the intensity decreases. 3. Determine Why does a The Electromagnetic Spectrum bright light have a high intensity?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright There are many kinds of electromagnetic wave other than light waves. Together, all these waves make up what is called the electromagnetic spectrum. The electromagnetic spectrum is the complete range of electromagnetic wave frequencies and wavelengths.

Reading Essentials 107 INCREASING WAVELENGTH Radio waves Infrared waves Ultraviolet waves Gamma rays

Microwaves X rays Visible light

INCREASING FREQUENCY

Picture This How is the electromagnetic spectrum 4. List Name three waves organized? in the electromagnetic Look at the ﬁgure above. At one end of the spectrum are spectrum that have the waves that have the lowest frequency. They have the different frequencies and wavelengths. lowest energy and the longest wavelength. At the other end of the spectrum are the waves that have the highest frequency. They have the highest energy and the shortest wavelength. All of the waves are the same kind of waves. They only have different frequencies, wavelengths, and energy. How are radio waves and microwaves used? Radio waves have the lowest frequency on the electromagnetic spectrum. They are on the left side of the electromagnetic spectrum in the ﬁgure above. They carry television and radio signals into your home. These waves have the longest wavelength. The wavelength of radio waves can range from 0.3 meters to thousands of meters long. The shortest radio waves are called microwaves. Microwaves have ●C Organize Information a wavelength of between 0.3 meters and 0.001 meters. Make the following Foldable Microwaves are used to cook food in microwave ovens. to help you organize the They also carry information to and from cell phones. information you learn about electromagnetic waves. How are infrared waves used? You use infrared waves when you use a remote control to Radio Waves & Microwaves change the channel on your television. Infrared waves carry Infrared Visible Light information from the remote control to the television. and Color Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Ultraviolet Infrared waves have wavelengths between 0.001 meters and Waves X Rays & 700 billionths of a meter. All warm bodies give off infrared Gamma Rays Electromagnetic waves. Special night goggles that pick up infrared waves can Waves from the Sun be used to locate people in the dark.

108 Waves, Sound, and Light Can people see electromagnetic waves? The part of the electromagnetic spectrum that people can see is called visible light. Visible light has wavelengths between 700 and 400 billionths of a meter. Find visible light on the electromagnetic spectrum on the previous page. The color of the light you see depends on the wavelength 5. Predict If you shine of the light wave. Violet light has the shortest wavelength. green light into a prism, will you see a rainbow? Why or Red light has the longest wavelength. The light from the Sun why not? or from a ﬂashlight is white light. White light is a combination of different colors. You can see this if you shine white light into a prism. When the light passes through the prism, each wavelength bends a different amount. You see this as a rainbow of different colors coming from the prism. What are ultraviolet waves? The next type of wave in the electromagnetic spectrum is ultraviolet waves. Ultraviolet waves are electromagnetic waves with wavelengths measuring between 400 billionths and 10 billionths of a meter. These wavelengths are shorter than those of visible light. Ultraviolet waves carry more energy than visible light waves. There are ultraviolet waves in sunlight that reaches Earth’s surface. Some exposure to ultraviolet waves is good for you. Ultraviolet waves help your body make vitamin D. You need vitamin D to keep your teeth and bones healthy. But, ultraviolet waves can give you a sunburn if you stay out in the sunlight too long. Too much exposure to ultraviolet waves can damage skin and even in some cases cause skin cancer. How are X rays and gamma rays used? X rays and gamma rays have the highest energy, highest frequency, and shortest wavelengths of all the waves in the electromagnetic spectrum. X Rays Have you ever had an X ray taken after an accident or a sports injury? Doctors use X rays to see broken bones. X rays have enough energy to go right through your skin. But, they cannot pass through dense objects, such as bones. 6. Explain Why are X rays used to make images of the This allows X rays to produce an image of the inside of bones inside the body?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright your body. X rays are also used to kill cancer cells. Gamma Rays Gamma rays have even more energy than X rays. Gamma rays are used on some foods to kill bacteria that make food spoil quickly.

Reading Essentials 109 What kind of electromagnetic waves come from the Sun? Most of the energy from the Sun is in the form of ultraviolet, visible, and infrared waves. These waves spread out over our entire solar system. Only a small number of them reach Earth. Earth’s atmosphere keeps most of the ultraviolet waves from reaching Earth’s surface. As a result, almost all the energy from the Sun that reaches Earth is transferred by infrared and visible electromagnetic waves. The Eye and Seeing Light Objects you see either reﬂect light or give off light. When this light reaches your eye, you see the object. The ﬁgure below shows what happens to light that enters your eye. First, light waves pass through a clear layer called the cornea (KOR nee uh). Then, the light goes through the lens, which is also clear. From the lens, the light shines on the back part of your eye called the retina.

Picture This Lens 7. Think Critically Why Retina does the light in the Pupil diagram bend when it enters the eye?

Cornea

Why do some objects have color? When visible light waves hit an object, some of the waves are reflected. The wavelengths of the light waves that are reflected determine the object’s color. For example, a red rose reflects light waves that have the wavelengths in the red part of the visible spectrum. A green leaf reflects the wavelengths that make green light. 8. Infer What color light Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright does a yellow shirt reflect? Some objects give off light. The color of objects that give off light is determined by the wavelengths they give off. For example, a neon sign looks red because it gives off red light waves.

110 Waves, Sound, and Light Lens Lens

The lens becomes ﬂatter when you focus on The lens becomes more curved when you a distant object. focus on an object nearby.

How does the eye focus on objects? Picture This The cornea and the lens help focus the light waves that 9. Describe What happens come into your eye. This lets you see a clear picture instead to the lens of your eye when you focus on an of a blurry one. The lens of the eye is ﬂexible. It changes object that is far away? shape to let you focus on objects that are nearby and far away, as shown in the ﬁgure below. Sometimes people need to wear glasses to correct their vision. Many people are nearsighted or farsighted. A person that is nearsighted can see nearby objects clearly. But objects that are far away are blurry. Nearsightedness results if the eyeball is too long. A farsighted person can see objects that are far away clearly. But they cannot focus on nearby objects. Farsightedness results if the eyeball is too short. What happens when light reaches the retina? When the light reaches the retina, special cells there send signals to your brain and you see objects. But how? The retina has millions of special cells called rods and cones. Rods help you see when there is not much light. Cones help you see colors. There are three types of cone cells. One type helps you see red and yellow light. Another type helps you see green and yellow light. The third type helps you see blue and violet light. Together, the cone cells help you see all the colors in an object. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 111 After You Read Mini Glossary electromagnetic spectrum: made of all the frequencies light: an electromagnetic wave that can be seen by the and wavelengths of electromagnetic waves human eye. electromagnetic waves: waves that can travel through ultraviolet waves: electromagnetic waves that have matter and through empty space wavelengths between 400 billionths and 10 billionths of a meter infrared waves: electromagnetic waves that have wavelengths between 0.001 meters and 700 billionths of a meter 1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence that tells how the electromagnetic spectrum and electromagnetic waves are related.

2. Complete the diagram with the information you learned from reading this section. Radio waves Use:

Use:

Electromagnetic spectrum Visible light

Use: Gamma rays Use: to kill bacteria on food

3. You highlighted the main idea of each paragraph as you read this section. How did you decide what to highlight each time? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about light.

112 Waves, Sound, and Light Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Minerals andproductsMinerals madefrom themare around all you. are madefrom minerals. and thesaltyou onfood, sprinkle glasses, such asmetalpots, Many day, you things useevery You caneven inyour findminerals home. around outdoors. You could justwalking findminerals to findthem?No. Would you have to crawl into acave into orgodown amine ofr more have than4,000minerals beenidentified. So far, can Theseproperties properties. Every mineral’s gives structure itunique distinctcrystal isoften seen inthemineral’sarrangement shape. crystal this orderly itsatoms, shows of theorderly arrangement amineral An Xray of atoms. of uniquearrangement its own rock. inanordinary asthegrains can alsobeassmall Minerals beautifulcrystals. in nature aslarge, that formed You canfindminerals such asplantsoranimals. ing things, liv- Inorganic usuallyare meansthatminerals notmadeof sal r aeu ftwo ormore minerals. usually are madeupof mineralsdefined? How are What isamineral? different?they How are gemsandrocks thesameandhow are have seen. andarock thatyou such asadiamond, Think aboutagem, section A Suppose you wanted to (MIHnuh rulz). lookforminerals Every mineral has its own particular chemical makeupEvery particular hasitsown and mineral chapter Read toLearn YouBefore Read mine 8 3 Also covers: Benchmarks—SC.D.1.3.1: r al ● SC.D.1.3.3; SC.D.2.3.2;SC.H.1.3.5;SC.H.1.3.6;SC.H.2.3.1;SC.H.3.3.5;SC.H.3.3.6 1 is a solid, inorganic material foundinnature. inorganicmaterial is asolid, Rocks andMinerals Minerals—Earth’s Jewels The studentknowsthatmechanicalandchemicalactivitiesshapereshapetheEarth’slandsurface. be usedto identifyminerals. R o c ks ● your class. information orquestionwith a questionabout.Sharethe you findinterestingorhave Use stickynotestomarkpages Sticky-note Discussions of minerals. you understandtheproperties sheets ofpaperasshowntohelp a layeredFoldablefromfour A ■ ■ What You’llLearn Find MainIdeas Study Coach minerals what arepropertiesof are different how rocksandminerals Properties ofMinerals cleavage andfracture Reading Essentials other properties streak orluster specific gravity hardness Crystals color Make 113 2. 1. 114 used toidentifyminerals? Determine Explain form. Rocks andMinerals one wayminerals What canbe formed round deposits of manganese crystals. manganese roundformed depositsof solutionand Themanganesefelloutof inthisway. formed ocean floorare covered manganesenodulesthat with the largeareas of For example, are deposited ascrystals. minerals Theextra solution. from thewater andfalloutof Any separate minerals extra dissolved minerals. amount of Water sihpuhTAY(prih canholdonlyacertain shun). crystals. form theminerals When thewater evaporates, dissolved inwater. are minerals Many kindsof remain. saltcrystals evaporates, the water If ocean water hassaltdissolved init. example, Magma atEarth’s surface iscalledlava. reaches whenmagma Minerals alsoform Earth’s surface. atoms combine inorderly minerals. patterns to form cools, As magma melted calledmagma. rock insideEarth identify friends by theirphysicalidentify friends properties. by inthe samewayidentify minerals theirproperties you from otherpeople. her apart You’ve identifiedyour by physical friend thatset properties you seeherface andrecognize away. herfeatures right Is around ityour turns Thentheperson and friend? friend. andhasthesamehaircolor andweight asyourheight Thepersonisthesame you. walkingaheadof see afriend fit together. andhow thecrystals crystal themineral look atthesize of To figure outhow wasformed, amineral dissolved minerals. therocks.probably inopenspaces formed within They space inwhich to grow. of hadplenty the mineral means crystals formed perfectly Large, cooled slowly. magma as formed grains Theselargemineral apuzzle. the pieces of have minerals Some thatfittogether like largegrains formed. How domineralsform? Properties ofMinerals Properties somecluestomineralformation? What are Minerals also form from alsoform Minerals aprocess precipitation called For water. of from form evaporation Some minerals from form minerals Some inseveral ways. form Minerals ahmnrlas a nqepyia rpris You can alsohasunique physicalEach mineral properties. You thinkyou youImagine are thestreet. walkingdown grow from in solutions rich crystals Some clusters of Sometimes justby you lookingatamineral cantell how it

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Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. do this because some minerals are todo thisbecausesome minerals harmful thebody. You shouldnot sometimes usetaste to identifyamineral. calcite, you seeadoubleimage. will you lookthrough apiece of If light. a doubleray of into light Calcite ray alsochanges of asingle to fizz. begins calcite comes into anacidlike contact with dilute HCl, clips justlike amagnet. metalpaper attract will magnetite Apiece of like amagnet. acts magnetite themineral For example, help identifythem. way you canidentifyminerals. isanother Measuring specificgravity each oneinyour hand. You could feelthedifference by holding heavier thanwater. Pure goldismore than19times times heavier thanwater. isaboutfive pyrite For example, water. equal volume of an of theweight with amineral compares of theweight Specificgravity are much heavier fortheirsize thanothers. Someminerals cube ismuch heavier thanthewooden cube. thelead bothcubesareis heavier? Though thesamesize, Which one lead. wood andtheotherismadeoutof out of identify thatmineral. Knowing amineral’s helpyou hardness will mineral. the common objectscanhelpyou determine thehardness of Using several common objectsislisted. The hardness of page. Lookatthetableonprevious mineral’s hardness. cannotscratchfluorite apatite (number 5ontheMohs scale). But scratch calcitescale) will (number 3ontheMohs scale). (number fluorite 4ontheMohs For example, other minerals. diamond. hardest mineral, thenumber 10isthe with Amineral talc. softest mineral, most minerals youmost minerals find. to Learn use themandyou canidentify to identifyminerals. What other properties helpidentifyminerals? What otherproperties What isspecificgravity? How istheMohsscaleused? Together, all the properties you alltheproperties Together, Scientists Halite taste. thathasasalty isamineral When it calciteThe mineral hastwo unusual properties. haveSome minerals otherunusual thatcan properties Oneismade twoImagine cubesthat are thesamesize. You canuseobjectsyou have athometo determine a A mineral’s hardness isdetermined by scratching itwith thenumber 1ontheMohs with A mineral scaleisthe have read about are used 8. 7. halite have? property doesthemineral Identify Determine of amineraltowhat? gravity comparestheweight Reading Essentials What unusual Specific 117 10. 9. 118 contain? elements doallsilicates gem? order tobeconsidereda must amineralhavein Classify Identify Rocks andMinerals What qualities What two That iswhy theones thatdoare rare andvaluable. standards. Few meetthesehigh minerals luster orcolor. Agemmust alsohave abeautiful orcracks. defects, flaws, It should nothave any must beclear. amineral agem, of To have thequality itabeautifulappearance. giving polished, omnmnrl,you beableto identifymostrocks. will common minerals, you to learn recognize these If rock-forming minerals. are Theseminerals asthe known therocks. up mostof onlyafewmake minerals, the4,000known But of minerals. scientists think diamonds form deep insideEarth’sscientists thinkdiamonds form mantle. For thisreason, greater thanany foundinEarth’s crust. Thispressure is pressure. diamonds by high usingvery Scientistshave to learned make synthetic conditions. A jewelry. diamondisagem thatisoften A usedin diamond ring. you would have rather a course, Of or adiamondring? when theancientseasthatcovered theMidwest evaporated. halite Themineral formed theMidwest. much of surface of isfoundinmany places. gypsum mineral Rock thatcontains the remained. gypsum the mineral When theseseasevaporated, ancientseas. on thebottom of thatispurea mineral silica(SiO is Quartz Silicates contain theelementssilicon andoxygen. fthecommon rock limestone. of calcite mineral makes carbonate The upmost and oxygen. areCarbonates compounds containing theelementscarbon feldspar. inEarth’s theminerals of are crust types of than half More inwhich otherelements. silicacombinesmineral with Common Minerals Why are gems sorare? Why are gems? What are someothercommonminerals? What are minerals? rock-forming What are Rocks thatmake are uphuge mountainranges madeof Gems are are rare becausethey madeunderspecial would you ring have—a rather ring quartz of Which type isfoundbeneaththe orrock salt, halite, The mineral Other common canbefoundinrocks minerals formed Most are rock-forming minerals silicates (SIHluhkaytz). Other important rock-forming minerals are rock-forming minerals carbonates. Other important g e m is a rare, valuable mineral thatcanbe cutand mineral valuable is arare, 2 .Feldspar isasilicate ).

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. process calledmining. ina Earth these usefulmetalsmust beremoved from Ores of comes from invitamins the magnesium dolomite. and comes theleadusedinbatteries from galena, example, For daymetals thathumans come useevery from ores. Many substance thatitcanbeminedandsoldforaprofit. mined with it. mined with metalsareThese harmful mixed phosphate andare with it. with andarsenic, such asuranium dangerous materials, creates problems. but italso into money Florida, brings phosphate industry The mainlyto make fertilizer. which isprocessed, phosphate, electronics. andmost andpans, pots wiring, products includeelectrical Copper industry. and businesses, products usedhomes, in of itismade into Then many types or purified. refined, is thecopper After smelting, unwanted are materials removed. theore is melted and In thesmeltingprocess, obtain copper. Smelting istheprocess usedto orelement. useful mineral below shows somecommon items collected andrecycled. figure The by mining. landthatisdisturbed the amountof Recycling alsolimits for miningandsaves resources. mineral metalinthisway decreases Conserving theneed products. used metalproducts are melted andmadeinto down new Old, metalisoften scrap reused orrecycled. For thisreason, are minerals considered anonrenewable resource. a result, What minerals are around you? around What mineralsare processed? ores How are How canmineralsbeconserved? ores? What are The process phosphate alsoburied thatburied is theworld’s Florida Central leadingproducer of itmust beprocessed to remove the After anore ismined, As inEarth’s minerals crust. There are limited amountsof An o r e samnrlta otiseog fauseful thatcontains of is amineral enough 11. 12. contains copper. everyday productthat Think Critically Apply metal products? it importanttorecycle Reading Essentials Name one Why is 119 3. 2. 1. mineral: gem: crystal: Mini Glossary 120 strategy helpyou you understandtheinformation aboutminerals? learned strategy How didthis you usedstickynotes to interesting mark pagesorquestions. As you read, Compare andgemsusingthis minerals Venn diagram. Use atleasttwo terms in your sentence. minerals. Write onesentence about Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section in anorderlypattern,anduniqueproperties always hasthesamechemicalmakeup,atomsarranged repeating pattern End of rare, valuablemineralthatcanbecutandpolished solid materialwithatomsarrangedinanorderly, Rocks andMinerals solid, inorganicmaterialfoundinnaturethat ieasGems Minerals Both games, andprojectstohelpyou learnmoreaboutminerals. Visit rock: ore: fl7.msscience.com material thatcontainsenoughofausefulmetalit or moreminerals can beminedandsoldforaprofit solid inorganicmaterialthatisusuallymadeupoftwo to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. in classifying igneous rock. igneous in classifying Thesetwo are categories important rocks are often basaltic. Extrusive igneous Intrusive rocks are igneous often granitic. rocks areigneous calledbasaltic(buh SAWL tihk)rocks. Dark-colored produce rock color. thathasadark anigneous will orcalcium, magnesium, rock thatcontains more iron, Melted NIHtihk)rocks. (gra rocks areigneous granitic call Light-colored color. produce alight rockwill with anigneous silica Melted rock thatcontains alotof the rock thatforms. andmetamorphic. sedimentary, rocks—igneous, produce thethree mainkindsof processes These are worn away andnew rocks form. What determines the colorofigneousrock? What determines (ihn TREW sihv) rock. igneous itiscalled coolsmaterial beneathEarth’s surface, When melted rock (ehk STREW sihv) rock. igneous (IHG neeus) Igneous Rock whenitcools?the material What doyou thinkhappensto it. explodingmaterial outof there isred-hot Often, volcano. Think aboutanerupting okmtra ol nErhssrae itiscalled rock cools material onEarth’s surface, When melted Earth’s surface from anderupts volcanoes. melted rock reaches Sometimes, cools andhardens. Earth section The chemicals inthemelted rock determine thecolor of to meltrock. itishotenough Deep insideEarth, rocks over time, Slowly, Rocks are constantly changing. chapter Read toLearn YouBefore Read 8 3 Also covers: Benchmarks—SC.D.1.3.3: ● 2 SC.D.1.3.1; SC.D.1.3.2;SC.D.1.3.5;SC.H.3.3.6 r Rocks andMinerals o Igneous andSedimentaryRocks c k forms whenmeltedforms rock from inside The studentknowshowconditionsthatexistinonesysteminfluencetheothersystems. ext int I r g r usi usi ne ous v v e e ● Two-Column Notes magma. rocks madefromlavaand organize informationabout following Foldabletohelpyou column, writedetailsaboutit. paragraph. Nexttoit,intheright write themainideasofeach columns. Intheleftcolumn, read, organizeyournotesintwo B What You’llLearn ■ ■ Classify Study Coach sedimentary rocksform how differenttypesof are different extrusive igneousrocks how intrusiveand Reading Essentials Magma Rocks Rocks from from Lava Make the As you 121 Picture This 2. 1. 122 rock forms. where theintrusiveigneous red penciltocirclethearea igneous rockforms.Usea where theextrusive the magmatoarea trace thepathof pencil to extrusive igneousrock? a rockisanintrusiveor you lookfortodetermineif Identify Describe Rocks andMinerals Use ablue What would Sometimes lava traps gas and forms rocks filled with holes. rocks andforms Sometimes lava filledwith gas traps volcanic form They glass. lava flows have atall. nograins Thefastest-cooling iscalledalava This flow. into water. lava oozes outonto theground or When afissure opens, from inEarth’sform cracks calledfissures crust (FIHshurz). Extrusive rocks alsomay igneous the airoronto thesurface. whenavolcanoform andshootslava erupts andashinto appearance. sometimesglassy, hard to seeandasmooth, rocks thatare usuallyhaveigneous crystals smallmineral extrusive As aresult, donothave timeto form. grains, or crystals, largemineral Since lava cools quickly, surface. rocksExtrusive from form igneous lava thatcools onEarth’s form aroundform avolcano. below shows where intrusive andextrusive rocks igneous Thefigure have magma timeto largecrystals. form the in minerals cooling The process issoslow, rock. igneous years to cool forthemagma andharden into millions of It cantake is forced upward butnever reaches thesurface. insideEarth magma of whenahuge glob form They Earth. cools rock below whenmagma forms igneous thesurface of How do rocks form from lava? from form How dorocks How do rocks form from magma? from form How dorocks Extrusive igneous rocks can form in two ways. They may They rocksExtrusive intwo canform igneous ways. itiscalledlava. When melted rock reaches Earth’s surface, etdrc nieErhi aldmga Intrusive Melted iscalledmagma. rock insideEarth Extrusive igneousrock Intrusive igneousrock

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. knGLAHM ruts). (kun rocks calledconglomerates detrital other sedimentsform Pebbles thatare mixed andcemented together with pebbles. sandstone. inapiece of can seetheseparate grains You sand-sized grains. are madeof such assandstone, rocks, silt-sized grains. up of rock made sedimentary Siltstone isadetrital and feelrough. make uparockgrains calledshale. Theseclay-sized are whenthey wet. feel slippery grains clay-sized smallest, The thatmake uptherock. the grains rock. sedimentary detrital Sandstone isacommon sedimenttogether into rock. of dissolvedminerals in water actlike cement to bindthelayers Other lower layers. or compact, top layers press down, As thelayers pileup, sedimentisdeposited. grain mineral Layer uponlayer of sediment anddeposittheminlayers. thesetiny of particles orwater carry ice, gravity, Wind, rocks. se are orotherrock calleddetrital particles grains rocks from thatform tiny Sedimentary mineral or ice. water, rocks thathave beenworn away by wind, tiny pieces of thin layer. a form they When thesedimentssettle, one place to another. thesesedimentsfrom andice canalsocarry water, Wind, grains. rock orrock mineral andice break pieces down of water, sediment. of the sandatbeach isatype For example, arematerials sediment(SEduhmunt). called How are detrital rocks identiﬁed? detritalrocks How are formed? detritalrocks How are Rocks Sedimentary okdtia dhTIth) hmcl andorganic. chemical, (dihTRItuhl), rock—detrital sedimentary There are three of maincategories forming. rocks are continouslymeans thatsedimentsandsedimentary This Rock isalways beingworn away onEarth’s surface. to form. rock years forsedimentary many thousandsoreven millionsof It takes from sedimentthatcollected inlayers to rock. form The roughest detrital sedimentary rock ismadeupof sedimentary The roughest detrital Rough sedimentary are evenSand-sized grains larger. largerthanclay-sized areSilt-sized slightly grains grains you usethesize of To rock, sedimentary identifydetrital or grains mineral rocks are madeof Some sedimentary Wind, inseveral ways. Sediment ismadeandtransported andother grains, mineral shells, rock, Tiny pieces of S e dime ntar y (sed uhMENtuhree) r o c k dimentary is made ● learn aboutsedimentaryrocks. Foldable asshowntohelpyou C 3. Classify smallest tolargest. grain sizesinorderfrom Classify Reading Essentials Chemical Organic Detrital Fossils Make afour-tab Write thefour 123 5. 4. 124 material formscoal? Identify minerals tobedeposited? in orderforitsdissolved What musthappentowater Draw Conclusions Rocks andMinerals What organic rocks thisway form whenthewater evaporates. Chemical halite The wasdissolved intheocean water. halite. or salt, of itleftbehindcrystals on your skinevaporated, When theocean water you. skin astheSun anddries warms ocean? You may have onyour noticed forming tiny crystals are minerals leftbehind. layers of As thehotwater onthesurface, evaporates underground. water reaches mineral-rich thesurface from deep when hot, rock. sedimentary thelayers chemical form Over time, layers are leftbehind. mineral When thewater evaporates, inminerals. that isrich those living today.those living thatlivedorganisms longagoandto compare themwith Scientistsusefossilsto study andorganic. chemical, detritus, have rocks. beenfoundinsedimentary are dinosaurbonesandfootprints fossilsthat For example, theonce-living plantoranimal. thebody of reveal much of thefossilsare largeand But sometimes, extremely small. rock are sedimentary organic thefossilsin Often, animals. once-living plantsand of Fossils are theremains ortraces limestone. inthe oceanalso form andare usuallyclassiﬁedas rocks sedimentary Organic thencoal forms. plant material, dead therock from isformed layers of If rock. to form thelayers are pressed together years, Over millionsof layers. theremains pileupin When matter living dies, rocks. produce electricity. rock isthecoal thatisusedasafueltosedimentary chalkboard rock? may alsobeasedimentary Another How do chemical sedimentary rocks form? rocks How dochemicalsedimentary Are fossils found in sedimentary rocks? fossilsfoundinsedimentary Are form? rocks sedimentary How doorganic Have you ever satintheSun inthe after swimming Some chemical rocks from orhotsprings form geysers rocks from form oceanSome chemical water sedimentary Fossils are found in all three types of sedimentary rocks— sedimentary Fossils of are three foundinall types limestone are madefrom fossils. of Chalk andothertypes sedimentary organic Chalk andcoal are examples of Did you know thatthechalk your teacher usesonthe

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. 2. 1. igneous rock: extrusive: Mini Glossary surface. lava onthe forms fromcooling ______rock formsfrommagmadeepinsideEarth. ______sedimentary rock? sedimentary Would to newinformation? again learn you usethisstrategy Did thetwo-column notes you madehelpyou about understandtheinformation Fill intheblanksboxes below. rock rock. andonesentenceabout igneous aboutsedimentary onesentence Thenwrite Review theterms andtheirdeﬁnitionsintheMini Glossary. After You Read from insideEarthcoolsandhardens form whenmeltedrockcoolsquicklyonEarth’ssurface igneous rocksthathavesmallornocrystalsand type ofrockthatformswhenmelted sedimentary rocks. games, andprojectstohelpyou learnmoreaboutigneousand Visit underground. magma forms fromcooling ______ﬂ7.msscience.com TWO TYPESOFROCK to accessyourtextbook,interactive of rock. grains ortinyparts forms frommineral ______sedimentary rock: intrusive: rock formsfromlayersofsediment. ______that collectstoformrocklayers rocks, dissolvedminerals,orplantandanimalmatter form whenmagmacoolsslowlybeneathEarth’ssurface igneous rocksthatusuallycontainlargecrystalsand that evaporates. dissolved inwater forms frommineral ______type ofrockmadefrompiecesother Reading Essentials animals. living plantsand remains ofonce- forms fromthe ______Section End of 125 information. you understandnew ideas ineachparagraphtohelp underline thekeywordsand ● Underline understand howrockschange. following Foldabletohelpyou D section 126 ■ ■ What You’llLearn chapter Organize by therockcycle that allrocksarelinked to form metamorphicrock for the conditionsneeded 8 3 Also covers: Benchmarks—SC.D.1.3.3:

Rocks andMinerals

Sediments

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Metamorphic Sediment Rocks andMinerals Make the Metamorphic RocksandtheRockCycle Rock

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ary The studentknowshowconditionsthatexistinonesysteminﬂuencetheothersystems. rsas l hs vnsmk e okoto old rock. Alltheseevents make newrock outof crystals. but it doeschange therock’s mineral doesn’t melttherock, the magma The heatof upinto moving Earth’smagma crust. Sometimesrocks are cooked by deeply orcontinents collide. take thatlongforpressure to build upwhilerocks are buried inrock. grains themineral make uprock andthesize of pressure andtemperature can change thechemicals that Changesin temperature depthinsideEarth. increase with Pressure and changes cancausecertain inrock. inside Earth pressure your body canchange ahatyou siton, pressure of rocks thatproduceand sedimentary newrocks. There are conditions igneous inbetween thesethatform temperature conditions molten thatform rock material. rocks Igneous are by formed high rock. bitsof away by low temperature processes thatbreak andwear down rocks are formed Sedimentary different physical processes. hnerock? change and temperature How dopressure OldRock New Rockfrom body changes thehat. your how Describe thepressure of accidentally sitonit. thatsomeoneleavesImagine ahatonchair andyou tcntk iloso er o ok ocag.It may years for rocks to change. It cantake of millions Just asthe rock isunder greatpressure. Deep insideEarth, areRocks constantly onEarth becauseof changing Read toLearn YouBefore Read

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. minerals inthenewrockminerals lineupinadistinctway. the Sometimes too. bechemically changed, but itmight newrock The notonlylooksdifferent, thatforms melted. but not whenexisting rockthat forms isheated orsqueezed, two maingroups—foliated (FOHleeay tud)andnonfoliated. Texture rock helpsto metamorphic into divide rock looks. rock’s texture isaphysical thatrefers to property how the A One way to identifyandgroup rock isby itstexture. rock. oreven othermetamorphic igneous, rock—sedimentary, rocks. pressure temperatures andhigh process theminto new where great Most rocks are recycled deepinsideEarth, years. The pelletslater canbemadeinto usefulnewproducts. are Thenthey heated andsqueezed into pellets. and cleaned. sorted, them intherecycling are bin?Firstthejugs collected, happensto after aboutwhat thesejugs youthought put they form the new kind of crystals foundinquartzite. crystals the newkindof form they When are squeezed andheated, thesandgrains sand grains. isanonfoliated rock Quartzite madefrom quartz rocks. are Soapstone nonfoliated andmarble any way. particular are they notlinedupin atall, are visible grains the mineral If can’tOften grains mineral be seeninnonfoliated rocks. are moreThey usually evenly colored thanfoliated rocks. nonfoliated rocks? What are foliatedrocks? What are grouped? metamorphicrocks How are form? How dometamorphicrocks foliated rock. metamorphic a slate, Somewalkways androofs are madeof foliated rocks. are andschist examples (SHIHST) of phyllite (FIHlite), (NISE), gneiss Slate, different-colored minerals. bands of Many foliated rocks have abook. of orleaves, like thepages, Foliated have minerals beenheated andsqueezed into layers, foliated under great pressureunder great temperature. andhigh good word forrocks are thatgetanewlookwhenthey The word N F New rocks from of metamorphic canform any othertype inaprocess thattakes millionsof Rocks are recycled too, Do you recycle your Have plasticmilkjugs? you ever oliat o nf M oliat comes from aLatinword thatmeans “leafy.” e e d tamo ok aevsbelyr fmnrl.Theword minerals. rocks have layers visible of e metamorphic d r rocks donothave distinctlayers orbands. p hic (me tuhMORﬁhk) en cag ffr. Thisisa form.” means “change of r o c k is newrock SC.H.1.3.1 ✔ 2. FC A T

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U U S S Identify Benchmark Check Annually Assessed Reading Essentials What would What type 127 Picture This 3. 128 Rock Cycle. three typesofrockinthe Instructions Interpret Scientiﬁc Rocks andMinerals Sediment Circle the Igneous rock Wearing awayandmoving by wind,water,andice Cooling osatycag ok.The constantly change rocks. related to oneanotherandhow different processes Scientists have madeamodelto show how allrocks are The RockCycle shown below. Therock cycle is years. rock cycle cantake millionsof Arock’s through the trip through therock cycle. journey Every ison anendless rock onEarth to another. one type rocks from changing shows theslow continuing process of Rocks are to another. constantly from changing onetype Melting Magma The RockCycle Wearing awayandmoving Wearing awayandmoving and cementingtogether by wind,water,andice by wind,water,andice Heat and pressure Compacting Melting r Melting o c k cy c Heat and pressure le Metamorphic rock Sedimentary rock is themodelthat

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. processes are now. takingplace right These therock cycle change rocks slowly over time. of rock forms. igneous extrusive a volcano and lava flows onto Earth’s surface, When explodes outof magma rockintrusive forms. igneous When cools below magma Earth’s surface, magma. form rock metamorphic may The eventually bemelted to rock. rock ischanged into metamorphic thesedimentary years, over millionsof Slowly, pressure temperature. andhigh rock. together to asedimentary form cementing thelayers Thepressure actslike glue, them. compacting the top layers presses onlower down layers, of weight The thelayers buildup. Over time, in thinlayers. thesedimentisdeposited Eventually, or maybe even by ice. orby by ariver thewind Thesedimentiscarried or sediment. itstiny grains, mineral of some breaking off rock, lava The rock. cools anigneous andforms lava. of glob to thesurface rises asa Themagma thefigure. bottom of rock. see thatany rock of into canturn any othertype You can rock itbecomes through thesedifferent processes. of Lookatthetypes andcementing together. compacting, cooling, melting, moving, away, wearing pressure, Theseprocesses includeheatand rock andchange it. Notice theprocesses thatactonthe through therock cycle. follow therock on thespotyou chose? From thatspot, rock is What of form Pick any spotontherock cycle model. What otherchangesoccur? What changesigneousrock? magma? from What forms ofarock? What isthejourney h yl fcag otne.Theprocesses thatare part change continues. The cycle of rock isundergreat thesedimentary Deep insideEarth, theigneous andice slowly wear away bits of rain, Wind, Now therock cycle tracing from atthe start themagma therock cycle page. on the previous Look atthefigure of 4. 5. lava? rock formsfromcooling Identify Predict sedimentary rock? changed intoanother sedimentary rockbe Reading Essentials How mightone What typeof 129 2. 1. metamorphic rock: foliated: Mini Glossary 130 Fill in the blanks in the chart below intheblankschart toFill show how rocks change. Use words atleasttwo vocabulary inyour sentences. rocks. about metamorphic onesentence Thenwrite Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section rock isheatedorsqueezed End of Rocks andMinerals metamorphic rocksthathavevisiblelayersofmineral and moving Weathering by wind, and ice water, away new rockthatformswhenexisting Cooling Melting Weathering away by wind,water, and moving and ice The RockCycle and cementingtogether Heat and pressure Weathering away by wind,water, Compacting and moving phic rocksandthe rockcycle. games, andprojectstohelpyou learnmoreaboutmetamor- Visit rock cycle: nonfoliated: and ice fl7.msscience.com layers orbands rocks changingfromonetypetoanother model thatshowstheslowcontinuingprocessof metamorphic rocksthatdonothavedistinct Melting to accessyourtextbook,interactive Melting Heat and pressure

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. likely to become fossils? Why become dothey fossils? Which organisms are more But somedeadorganisms dobecome fossils. isleft. no trace In time, Fungi may andbacteria causetheremains to rot. deadorganisms. animals may eatandscatter theremains of became extinct. andwhenorganisms and animalsﬁrstlived onland, plants when fossils to determine whenlifeﬁrstappeared, Scientistshave used organismsthatdiedlongago. of traces and even microbes. the pastandcompare today. organismsliving themwith canusefossilsto They study organismsthatlived in remains. fossil aboutextinct animalsfrom canlearn their study fossils, scientistswho Paleontologists, like? Theanswer isfossils. know were thatthey real? How doyou know were what they But how doyou animals thatlived inthepast. onEarth Formation ofFossils Formation oftheDistantPast Traces Earth’s history? What beusedasarecord might things of too. hasahistory, Earth own. they andotherthings letters, You aboutaperson’s canlearn by lookingatphotos, history section otaiasadpat ea onatrte i.Some Most animalsandplantsdecay soonafter die. they eietr okmycnanfsiso lns animals, plants, rock may containSedimentary fossilsof It’s likely thatyou’ve read aboutdinosaursandother chapter Read toLearn YouBefore Read 9 3 Also covers: organisms areproducedbytheoldones. Benchmarks— ● SC.B.2.3.2; SC.D.1.3.1;SC.D.1.3.3;SC.D.1.3.5 1 Clues toEarth’sPast SC.D.1.3.2 Fossils F Annually Assessed: ossils r h ean,ipit,or imprints, are theremains, The studentknowsthatoverthewholeEarth,organismsaregrowing,dying,anddecayingasnew ways thatfossilsarepreserved. to compareandcontrastthe Make aFoldableasshownbelow ● Two-Column Notes column, writedetailsaboutit. paragraph. Nexttoit,intheright write themainideaofeach columns. Intheleftcolumn, read, organizeyournotesintwo A Compare andContrast ■ ■ ■ What You’llLearn Study Coach forms andenvironments changes inEarth’slife how fossilsexplain tell rockages how fossilsareusedto how fossilsform Reading Essentials

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Mineral As you 131 2. 1. 132 remains? form permineralized source ofthemineralsthat than softpartsdo? chance ofbecomingfossils organisms haveabetter reason thathardpartsof Identify Explain Clues toEarth’sPast What isone What isthe adprso organisms. of hard parts Most fossilsare the decay more do. slowly thansoftparts Hard also parts are lesslikely to beeaten thansoftparts. Thesehard parts becoming fossils. have abetter chance of aloneisn’tquick burial always to make enough afossil. But rock. thefishmay become afossilinlayer of time, Over animals orwaves could getto itand tear itapart. no it by sedimentdroppedis quicklyburied from astream, If alake. sinkto thebottom adeadfishmight of example, For be protected thebody quickly. isforsedimentto bury Oneway adeadorganismcan remains must beprotected. yeo fossil. of type Theresult isa seep into thesespaces anddepositminerals. groundwater can is buried, thehard part If spaces. empty decay andleave thesoftparts When organismsdie, air. or nerves, bloodvessels, cells, the spaces canbefilledwith When organismsare alive, have tiny spaces in them. shells, organismspreserved asfossils? of bones andotherparts How are who draw dinosaursstudy theirfossilized bones. Artists dinosaursinbooks. You may have of seendrawings looking attheseremains. People aboutthepastby canlearn remains. permineralized fossilorganisms. pound thatreplaces of thehard parts How dofossilsform? How do minerals help form fossils? How domineralshelpform ofPreservation Types lc.Silica (S place. isleftinits themineral After theweather dissolves theshell, adeadorganism. flow might through theshell of minerals Water dissolved with fossilorganisms. of the hard parts replace Sometimesminerals theorganism. genetic code of DNA the isthechemical thatcarries materials. original someDNA canbefoundinthe At times, groundwater. It from isenclosedintheminerals the be preserved. from material theorganism’sSome original also body might fromthe spaces minerals insideare groundwater. filledwith raim ihhr at,sc sbns hls orteeth, shells, such asbones, hard parts, Organisms with its In order foradeadorganismto become afossil, h adprso iigtig,sc sbns et,and teeth, such asbones, things, living of The hard parts adinosaurinmuseum. You may have seenthebonesof Bones, wood, and other materials can become andothermaterials wood, Bones, P i O e r 2 mine ) dissolved inwater isonechemical com- r aliz e d r e mains are fossilsinwhich

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. of carbon leftfrom carbon anorganismandpreserved asafossil. of how a cast forms when a mold fills with minerals. how whenamoldfillswith acastforms figure The below shows fill amoldandharden into rock. okta ssae ietebd at A rock that isshapedlike thebody part. inthe orcavity, Thisleaves ahole, organism’s hard parts. water canflow through thesespaces andbreak the down Air and There may be smallspaces intherock. into rock. thesedimentturns In time, soft sedimentandgetburied. plantis usuallylost. theoriginal of The structure butitdoesn’t show much aboutthepast. fossil, a kindof Coal is into plantmaterial coal. inthicklayersthe carbon of heatandpressure change years, Over of millions swamps. A theorganism’s body. like an outline of isleft, carbon of orfilm, Athinlayer, organism. the heat andpressure force andliquidsoutof thegases all As sedimentbuildsup, adeadorganism. sediments bury Fossils when usuallyform fossils contain onlycarbon. bet A object. theoriginal of or cast, produces This acopy, new rock. inthe rock. cavity leaving a or dissolves, decays, anorganism when that forms What aremoldsandcasts? What iscoal? What arecarbonfilms? oeie h adprso adeadorganismfallinto a of Sometimes thehard parts may deadplantmaterial buildupin Large amountsof Some organismscontain living carbon. The tissuesof Later, water and minerals may water andminerals enter themoldandform Later, dissolves Shell cast is a type of fossil that forms whenminerals fossilthatforms of is atype forms Mold Minerals l mold fill car b o n mold results fi A cast lm is athinfilm is afossil Picture This 4. 3. fossil ontheright? shell ontheleftandcast difference betweenthe mold inarocklooklike? Explain Describe Reading Essentials What isthekey What doesa 133 6. 5. 134 different tracefossils. Define Identify fossils? Clues toEarth’sPast What areindex List three remains have tardeposits. beenfoundinnatural Someoriginal preserved infrozen ground inSiberia. have found been such asthemammoth, organisms, Some surrounds andprotects theinsect’s parts. original Theamber into atree sapthatturns asolid. in amber, Insects canbetrapped anorganismto bepreserved. of parts that existed for a short time. They are They calledindex fossils. time. that existed forashort organisms aboutthepastfromScientists canlearn thefossilsof time. specieschanged Other alotin short changing. without Somespecieslived foralongtime onEarth today. living organismsthatlived inthe pastandthose of and similarities more abouttheanimalwhodugburrow. scientistscanlearn From thisinformation, animal lived in. burrows canreveal how thesedimentwasthat the firm Fossil have dinosaurmight stalked another. of one type life. animal’s way of Thesefossilsgive scientists cluesaboutan moved andlived. or any thattell marks something abouthow ananimal burrows, trails, Trace fossilsmay befootprints, fossils. trace are They have thosetracks beenpreserved. Someof mud. How areoriginalremainspreserved? What doindexfossilsreveal? Index Fossils What aretracefossils? time period where overlap.time period thefossilranges therock layer isthe estimated The age of rock. sedimentary three different fossilsin which shows thetimespansof thenext page Lookatthefigure atthetop of appears. comparing timespansinwhich more than onefossil It isdoneby to estimate theserocks when formed. contain.they rock layers basedontheindex fossils estimate theagesof scientistscan this, Becauseof aspecifictime. during Organismsthatbecame index fossilslived only many places. andwere foundin were numerous, time, forashort Earth rmtm otm,conditions forthesoft are justright From timeto time, I Fossils show thedifferences Species have changed over time. dinosaurstraveled orhow Tracks cantell how herds of insoft Animals thatwalked longagolefttracks onEarth u o l ok aeidxfsis There isanotherway But notallrocks have index fossils. nd ex f ossils r h ean fspeciesthatexisted on are theremains of

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. that existed whentherocks formed. abouttheclimate scientistslearn andenvironment fossils, By studying therock layers. them andabouttheages of provide abouttherock information They layers thatcontain aboutplantsandanimalsthatareinformation now extinct. North America. covered thisarea of ashallow seamust have werethe fossilcrinoids living, What from doscientistslearn thesefossils? When America. western North andcentral of inparts found indeserts have crinoids been But fossilsof shallow waters. warm, these plantswere living. scientistsknow thattheclimate was tropical when fossils, these Becauseof thisarea isn’t tropical. environment of But today the tropical plants. States contain fossilsof theeastern United of rocks inparts For example, area. water was. even bepossibleto itmight how learn deepthe ocean, thearea wascovered by If was landorcovered by anocean. can determine whetheranarea they Using fossils, long ago. found inadesert? Why mightfossilsofseaanimalsbe Fossils andAncientEnvironments osl iecusaotps ieo at.Fossils give Fossils give cluesabout pastlifeonEarth. many areCrinoids thatusuallylive animalswith arms in an Fossils alsocangive cluesaboutthepastclimate of Scientists canusefossilsto whatanarea learn waslike Fossils inaSequenceofSedimentaryRock

M illions of years ago 5 44 41 360 3 2 2 86 0 0 5 Euom Fossil Ran p halu s Ill g a e Char en us Rhi t p idomell a Picture This 7. 8. on Earth? organisms existtogether of timedidallthree the chart,duringwhatspan Interpret Infer mountains? rock layersthatformthe does thattellyouaboutthe mountains today,what are foundonthetopsof Reading Essentials If fossilsofseashells According to 135 2. 1. fossil: cast: carbon film: Mini Glossary 136 vides aboutthepast. vides oneclueitpro- fossilandwrite of Identify each type Complete theconcept map below. explains why amoldandcastfossilmay befoundin thesamearea. asentence Thenwrite that Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section preserved asafossil that diedlongago minerals andthenhardensintorock End of a fossilthatformswhenmoldfillswithsedimentor the remains,imprints,ortracesofanimalsplants Clues toEarth’sPast thin filmofcarbonleftfromanorganismand Shows thecompletestructureof an organismfromthepast Original remains Carbon films of fossils Types games, andprojectstohelpyou learnmoreaboutfossils. Visit permineralized remains: mold: index fossil: fl7.msscience.com dissolves andleavesacavityintherock filled withmineralsfromgroundwater time, werenumerous,andfoundinmanyplaces a fossilthatformswhenanorganismdecaysor the remainsofspeciesthatlivedforashort to accessyourtextbook,interactive fossils inwhichthespacesare

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. disappear from Earth. wantto They know to whatcaused thetrilobites puzzle. canhelppiece they together a fossils, trilobite studying Thestudentshopethatby time. geologic of specific periods theworld during livedbecause they over of vastregions Trilobites are considered to beindex fossils ancient seas. hard-shelled animalsthatlived in Trilobites are small, lohbites). (TRI organismscalledtrilobites to findfossilsof hope they years old, of millions rocks thatare hundreds of eti eid.The periods. certain thatexistedtime unitsbasedonlife-forms onlyduring Paleontologists Earth’s divide into history time. geologic throughout Earth’s events in important marks history What isthegeologictimescale? Geologic Time decades? Explainyour answer. or years, units would bebestforthistimeline—minutes, What your life. Suppose you wantto make atimelineof methods to define a division of geologic time. geologic methods to of defineadivision useother paleontologists Then remain from aperiod. Sometimesfewfossils timeinEarth’s history. of divisions section The appearance ordisapp By lookingin studentsissearching forfossils. A group of chapter Read toLearn YouBefore Read 9 3 Also covers: organisms areproducedbytheoldones. Benchmarks—SC.D.1.3.2 AnnuallyAssessed: ● 2 SC.D.1.3.1; SC.D.1.3.3;SC.D.1.3.5 Clues toEarth’sPast Life andGeologicTime g e olo g ic aac ftpso organisms of types earance of t ime The studentknowsthatoverthewholeEarth,organismsaregrowing,dying,anddecayingasnew scale is madeupof ● Communicate their characteristics. and eventsintogroupsbasedon organize geologictimeperiods following Foldabletohelpyou information inthetext. each otherunderstandthe main ideaoftheparagraph.Help saying somethingaboutthe paragraph ofthetext,taketurns partner. Asyoureadeach B What You’llLearn ■ ■ ■ Classify Study Coach affects species how platetectonics time divisions ingeologic organisms canshow how changesin divided how geologictimeis Reading Essentials Make the Work witha 137

Hadean Eon Hadean

3,800

Archean Eon Archean

2,500

Proterozoic Eon Proterozoic

544

Cambrian Period Cambrian

Picture This ,500 ,500 505 2. 1. 138 Origin ofEarth

of theMesozoicEra? event occurredattheend geologic time? longest subdivisionof Interpret Identify Ordovician Period Ordovician

Clues toEarth’sPast 440

First life Silurian Period Silurian

Precambrian 410 What isthe

Time

What major

is rlbtsFirstfloweringplants First trilobites Devonian Period Devonian

360

Mississippian Period Mississippian

325 Pennsylvanian Period Pennsylvanian

Paleozoic Era 286

ipyery ide orlate. middle, simply early, ormay becalled like thoseintheCenozoic Era, names, Epochs may begiven from continentvary to continent. butthesemay also characterized by differences inlife-forms, existed allover theworld. life-forms of types which certain timeduring geologic present inrocks. Thiscanbeseeninthefossils reptiles becameextinct. mammalsand birds, invertebrates, many kindsof Era, theMesozoic attheendof For example, organisms present. of ismarkedera by majorworldwide changes inthetypes fossils. certain abundance of Eonsare andare thelongestsubdivision basedonthe time. geologic The ﬁgure below shows of themajorsubdivisions can userocks containing time. fossilsto geologic subdivide to whenorganismsbeg form subdivide geologic time. geologic subdivide there to islittleinformation helpscientists other cases, In year. asingle rock during thatformed different layers of Sometimesitispossibleto distinguish being studied. rock record thatis It dependsonthekindof subdivided. What aremajorsubdivisionsofgeologictime? What limitsthedivisionsofgeologictime?

Permian Period Permian An epoch is are into periods divided epochs. Geologic isaunitof Aperiod are intoEras subdivided periods. An Eons are callederas. into divided smallertimeperiods Fossils began containThe oldestrocks nofossils. onEarth There isalimitto how timecanbe ﬁnelygeologic

248

Triassic Period Triassic

213

Jurassic Period Jurassic

Phanerozoic Eon Phanerozoic 145 Mesozoic Era

Mass extinction

Cretaceous Period Cretaceous 55.5

nt pero at.Scientists an to appearonEarth. Epoch

Paleocene

Epoch 33.7

Eocene

Epoch Period

23.8 Cenozoic Era

Oligocene Tertiary

Epoch

5.3

Miocene

Epoch

Pliocene

1.8

Epoch

Pleistocene

0.008

Epoch

Holocene

Period

Quaternary Millions of years ago years of CopyrightMillions © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. kinds of trilobites that lived trilobites different during periods. kinds of changes intheirenvironment. Thechanges alsotell how responded trilobites to lived. changes tell how different from trilobites different periods These explain how evolved trilobites over time. geologic species. thatwere characteristics particular different from allother haditsown trilobites Each species of trilobites. species of thePaleozoic haddifferent Era of Different periods evolved. trilobites becameextinct andothernewspeciesof trilobites somespeciesof Allthrough thePaleozoic Era, million years. t trilobites tellscientists? What dothechangingcharacteristicsof Trilobites into sections (thorax). They alsohave They atail(pygidium). into sections(thorax). have They ordivided thatissegmented amiddle (cephalon). Thebodieshave ahead inadifferentthree way. parts itsbody. run the lengthof calledlobes, three The parts, shell. thetrilobite of parts ﬁgure The below shows thethree have shell. athree-part ancient animalswere given becausethey thenametrilobite These An exoskeleton isahard outer skeleton. exoskeleton. r ilo h gr ttetpo thenext pageshows thedifferent The ﬁgure atthetop of Paleontologists usethedifferences species to intrilobite Trilobites lived inEarth’s oceans for more than200 Remember you thetrilobites read aboutearlier? A The bodies of trilobites also can be described ashaving alsocanbedescribed trilobites The bodiesof bit e (SE fullahn) Cephalon is an ancient organism with athree-lobed is anancientorganismwith (THOR aks) Thorax (pi JIHdeeuhm) Pygidium Side lobe Middle lobe Side lobe Picture This SC.D.1.3.2 ✔ FC 3. A T

middle, andtail. blue pencil,circlethehead, the trilobite’slobes.Witha With aredpencil,outline the pictureofatrilobite.

Identify

F F

O O

4. the PaleozoicEra? to trilobitespeciesduring things werehappening C C

U U S S Identify Benchmark Check Annually Assessed Reading Essentials Look carefullyat What two 139 Picture This 6. 5. 140 lived? different trilobitespecies scientists figureoutwhere characteristic helps Identify Describe Mississippian period. Cambrian periodandthe between trilobitesinthe Clues toEarth’sPast What the differences of the body. Later trilobites hadfewer Later trilobites segments. thebody. of specieshad early trilobite alsocould They seetheirworld well. very their head. species developed complex eyes onstalksthatextended from Stillothertrilobite hadexcellent Thesetrilobites vision. lenses. hadcompound manytrilobite eyes—eyes with individual Onespeciesof complexspecies developed highly eyes. where there wasnolight. thedeepocean have might They lived of inapart floor. have might trilobites burrowed into sedimentsontheocean blind These theireyes disappeared completely. Eventually, many speciesbecamesmallerandsmaller. trilobite eyes of andcrawling ontheoceanswimming floor. clue shows were thattrilobites adapted to bothactive This thehead. midway between thefront andthebackof hadeyes thatwere trilobites Most speciesof theocean. of itlikely lived onthebottom head, its toward thebackof itseyes are located it If itshead, likely swamactively through thesea. eyes are inthefront of its If about how itlived. anorganism’s eyes give clues The positionof selection. natural Trilobite eyes show theresult of complexwith eyes. What changes occurred intrilobitebodies? What changesoccurred intrilobiteeyes?What changesoccurred What dotrilobiteeyes reveal? h rlbt oyas hne vrgooi ie Some body alsochangedThe trilobite over time. geologic Sometrilobite Not specieslosttheireyes. alltrilobite the Gradually, changed. theeyes intrilobites Over time, Trilobites may have beenthefirstorganismsonEarth Cambrian Period Ordovician Period Silurian Period many inthemiddlepart segments Devonian Period Mississippian Period

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. After You Read Mini Glossary geologic time scale: divisions of time in Earth’s history trilobite (TRI loh bite) : small, hard-shelled animal that lived in ancient seas

1. Review the terms and their deﬁnitions in the Mini Glossary. Then write two sentences explaining how the geologic time scale relates to what you learned about trilobites.

2. Fill in the correct term to show how the Geologic Time Scale is divided.

Phanerozoic Eon a. ______

Mesozoic Era Cenozoic Era b. ______Quaternary Tertiary Period Period

Cretaceous Period c. ______Jurassic Period Triassic Period Pleistocene Paleocene Oligocene Holocene Pliocene Miocene Eocene Epoch Epoch Epoch Epoch Epoch Epoch Epoch d. ______

3. You just read a few pages of information about trilobites. Why are they so important? Explain what you have learned about the importance of trilobite fossils. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Visit ﬂ7.msscience.com to access your textbook, interactive End of games, and projects to help you learn more about life and Section geologic time. Reading Essentials 141 chapter Clues to Earth’s Past 93 section ●3 Relative Ages of Rocks Benchmarks—SC.D.1.3.3: The student knows how conditions that exist in one system inﬂuence the conditions that exist in other systems. SC.D.1.3.5: The student understands concepts of time and size relating to the interaction of Earth’s processes. Also covers: SC.H.2.3.1

What You’ll Learn Before You Read ■ how to tell the relative ages of rock layers Think of two friends. You want to know who is older. Without ■ how to interpret gaps in knowing their birthdays, how could you ﬁgure out who’s older? the rock record

Study Coach Read to Learn Make Flash Cards As you read this section, make flash Superposition cards for each main topic. On one side of the card, write the Imagine that you see an interesting car drive by. Then you topic. On the other side, write remember seeing a picture of the car in the January edition key information. of a magazine you have at home. In your room is a pile of magazines from the past year. As you dig down through the pile, you find magazines from March, then February. January must be next. How did you know that the January issue would be at the bottom? Where are the oldest rock layers? To find the older magazine under newer ones, you used the principle of superposition. How does this principle apply to rocks? The principle of superposition states that in layers of rock that have not been disturbed, the oldest rocks are on the bottom and the rocks become younger toward ●C Compare Make a three-tab Foldable to compare the top. Scientists use this principle to help find the ages of the concept of relative age to layers of rock. the principle of superposition. How do rocks layers form? Sediments build up, forming layers of sedimentary rock. The first layer to form is on the bottom. A new layer forms on top of the first one. A third layer forms on top of the Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright second layer. The bottom layer is the oldest, because it was formed first. Sometimes, the layers of rock are disturbed. When layers have been turned upside down, other clues are needed to tell which rock layer is oldest.

142 Clues to Earth’s Past Relative Ages Remember the old magazine you were trying to find? What if you want to find another magazine? You don’t know how old it is, but you know it came after the January issue. You can find it in the stack by using the principal of relative age. The relative age of something is its age in comparison to the ages of other things. Geologists figure out the relative ages of rocks by studying 1. Identify What term their places in a sequence. For example, if layers of describes the age of sedimentary rock have been moved by a fault, or a break in something compared with Earth’s surface, the rock layers had to be there before the the ages of other things? fault cut through them. So, the relative age of the rocks is older than the relative age of the fault. Relative age doesn’t tell you how old the rock is in actual years. The rock layer could be 10,000 years old or one million years old. The relative age only tells you that the rock layer is younger than the layers below it and older than the fault cutting through it. How do other clues help? It’s easy to figure out relative age if the rocks haven’t been moved. Look at the figure below on the left showing rock layers that haven’t been disturbed. Which layer is the oldest? Picture This According to the principle of superposition, the bottom 2. Interpret Highlight the layer of limestone in both layer is oldest. figures. Which rock layer Now look at the figure on the right where the rock layers probably has the oldest have been disturbed. If a fossil is found in the top layer that fossils? is older than a fossil in a lower layer, it shows that the layers have been turned upside down. This could have been caused by folding during mountain building.

Limestone Limestone Coal Coal

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Sandstone Sandstone Undisturbed Layers Folded Layers

Reading Essentials 143 Picture This 4. 3. 144 in therocklayerscalled? Highlight Identify figure. unconformity inthelast Clues toEarth’sPast What aregaps the angular These gapsintherock layers are called layers bemissing. might Layers of orparts may notbewhole. l h aesaeprle,therock record stillhasagap. all thelayers are parallel, Even though surface whensedimentswere deposited again. younger rocks above formed theerosion Later, and eroded. At onetimetherocks were exposed erosion. an oldsurface of Careful study reveals rock layers. sedimentary horizontal of angular unconformity. results whennewlayers ontilted form layers iscalledan that unconformity The thetilted anderoded layers. of rock are deposited sedimentary ontop layers new of Later, erosion wear thetilted andweathering down rock layers. Over time, rock inthefigure asshown below. sedimentary Unconformities Why wouldalayer ofrockbemissing? Sedimentaryrocksaredeposited 1. What areangularunconformities? unconformities. of There are three types away. erosion removes rock layers by them washingorscraping Unconformities develop when kunFORmuh teez). (un .Tetle aeseoe .Anangularunconformityresults 4. Thetilted layerserode. 3. originally ashorizontallayers. aeso okfr eodo h at But therecord thepast. rock arecord form of Layers of oeie a aeso rock canbemissingfrom astack Sometimes flatlayers of Forces below Earth’s surface canliftandtiltlayers of .Thehorizontalrocklayersaretilted 2. the tiltedlayers. when newlayersaredepositedon as forceswithinEarthdeformthem. Angular unconformity unc o nf o r mit ies

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. hrfr,pr fthe samedeposit. of part therefore, can show thattherock ineach place isthesameage and, it fossilsare foundinthe rock layers inboth places, of types thesame If layers canalsobematched usingfossilevidence. The Walking alongalayer canprove itisunbroken. next. isto walkalongthelayerfar apart from oneplace to the or correlated. rocks canbematched thatare up, farapart of layers Often, rock are inbothlocations. the samelayers of that theorize they Basedontheirobservations, sandstone. limestone, area andfindthesamesequence—sandstone, return to They thefirst sandstone. then anotherlayer of limestone and Above thesandstone isalayer of location. that lookslike thesandstone studiedinthefirst they sandstone alayer observe they of at anarea 250kmaway, surface isanonconformity. between thetwo rock types The theerosion surface. are thendeposited ontop of rocks Sedimentary rocks areigneous uplifted anderoded. or occurs metamorphic Anonconformity when below. What evidence can correlate rocklayers?What evidence cancorrelate Matching UpRockLayers What arenonconformities? Disconformity iepse ihu n e aeso rock forming. anytime passeswithout newlayers of of whenalongperiod alsoforms Adisconformity below. inthefigure shown iscalledadisconformity, unconformity disconformity of erosion—a Old surface nonconformity of erosion—a Old surface One way to correlate rock layers from two places thatare Later, sandstone. Suppose scientistsare alayer studying of inthefigure isshown unconformity of Another type When a flat rock layer is missing, this type of thistype When aflatrock layer ismissing, Sedimentary rockdepositedontopoferodedsurface Newer layersformedassedimentsweredeposited underneath rock metamorphic Igneous or and below layers above Parallel rock Picture This Picture This 5. 6. disconformity. Identify Determine rock blue. Color thesedimentary color theupliftedrockred. Reading Essentials Highlight the In thefigure, 145 After You Read Mini Glossary principle of superposition: states that in undisturbed rock relative age: age of something compared to the age of layers, the oldest rock is at the bottom and the rocks are other things younger toward the top unconformity: a gap in the rock layers due to erosion or a period without rock deposit

1. Review the terms and their deﬁnitions in the Mini Glossary. Choose one term and explain in your own words what it means.

2. Look back at the question you answered for the “Before You Read” at the beginning of this section. Explain how ﬁguring out which of your friends is older is connected to ﬁnding relative age.

3. Complete the table about unconformities.

Unconformities

Type Description Causes

Angular unconformity

Erosion of whole layers or no new deposition Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Sedimentary rock layers over igneous or metamorphic rock

146 Clues to Earth’s Past 4. The diagram below shows rock layers in two different locations: Bryce Canyon and Canyonlands National Park. Date deposited (millions of years ago) Bryce Canyon Wasatch Fm 2–65 National Park Kaiparowits Fm 65–136 Canyonlands Straight Cliffs Ss National Park Morrison Fm Dakota Ss Winsor Fm 136–190 Entrada Ss Entrada Ss Carmel Fm Navajo Ss Navajo Ss Wingate Ss Older rocks 190–225 Chinle Fm not exposed Moenkopi Fm

225–280 Cutler Gp Rico Gp 280–320 Hermosa Gp a) What are the names of the rock layers that are the same in both of these locations?

b) Suppose you found a fossil in the top layer of the Canyonlands rock formation. It is the fossil of an organism that only existed on Earth for a short time. In which rock layer of Bryce Canyon could you look in to ﬁnd a similar fossil? Explain your answer.

5. As you read this section, you made ﬂash cards to help you learn. How did the ﬂash cards help you learn about how layers can be correlated? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Visit fl7.msscience.com to access your textbook, interactive End of games, and projects to help you learn more about the relative Section ages of rocks. Reading Essentials 147 dating. decay, half-life,andradiometric explain absoluteage,radioactive sheets ofnotebookpaperto definition. each vocabularytermandits you readthissection,highlight ● Highlight Key Terms D section What You’llLearn 148 ■ ■ chapter Explain a rock’sage isotopes areusedtotell how thehalf-livesof differs fromrelativeage how absoluteage 9 3 Also covers: and decayingasneworganismsareproducedbytheoldones. Benchmarks—SC.D.1.3.2 AnnuallyAssessed: Absolute Half-life Clues toEarth’sPast Age ● Use quarter- 4 SC.A.1.3.5; SC.A.2.3.2;SC.D.1.3.3;SC.D.1.3.5;SC.H.1.3.1;SC.H.1.3.2;SC.H.1.3.3;SC.H.1.3.4;SC.H.1.3.6;SC.H.1.3.7;SC.H.2. Clues toEarth’sPast Radiometric Radioactive Absolute AgesofRocks Dating Decay As events inEarth’s history. rocks leads to abetter understandingof absolute ageof Knowing the time haspassedsince therock wasformed. someatoms give goodcluesabouthow much of properties The atoms inrock to material determine absolute age. of usetheproperties Geologists rocks. out theabsolute ageof are ableto figure orgeologists, Scientists whostudy rocks, A magazines backinorder. you canputthe By usingthedates asyour guide, job easy. dates The make your magazines have dates ontheircovers. allthe the bottom andthenewest are onthetop? Luckily, according to theirrelative age. are They nolongerinorder arethey allinajumble. By now, need to getyour magazinesbackinto aneatpile. you decide thatyou aboutthecaryou saw, for thatarticle What isabsoluteage? Absolute Ages your exact age. tell different ways you could prove is? Onthelinesbelow, How oldare you? How doyou know your what exact age The studentknowsthatoverthewholeEarth,organismsaregrowing,dying, bsol ok o’ aedtssapdo hm Ordothey? Rocks don’t have dates stampedonthem. How canyou stackthemagazinessooldestare on magazineslooking After through you your sort stackof Read toLearn YouBefore Read u t e ag e steae nyas farock orotherobject. of inyears, is theage, 3.1; SC.H.3.3.5

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. h ulu fanatom breaks down. the nucleus of beta decay are inthefigure shown below. Alphaand Thisiscalledalphadecay. analphaparticle. of two protons andtwo neutrons intheform isotopes give off Other The nucleus losesaneutron butgainsaproton. decay becausetheelectron leaves theatom asabetaparticle. radio of type This and anelectron. energy. a lotof hydrogen. there are three isotopes of Thismeansthat ortwo neutrons. oneneutron, no neutrons, Hydrogen atoms canhave one proton isahydrogen atom. just atom with every For example, orisotope. the element, neutrons of determines theform Thenumber of element. the protons of determines theidentity The number of which have charge. noelectric andneutrons, positive charge, which have a protons, Thenucleus ismadeupof electrons. negatively particles charged called surrounded by acloudof What arealphaandbetadecay? Radioactive Decay Unstable parent Unstable parent nsm stps aneutron breaks into down aproton In someisotopes, off giving Some isotopes break into down otherisotopes, which is Every atom hasadensecenter calledthenucleus, isotope isotope Proton Neutron Neutron R adio Alpha decay Beta decay act i v e d e ca y is theprocess inwhich active decay iscalledbeta Daughter Daughter product product Proton Beta particle (electron) particle Alpha Picture This 1. 2. breaks down? nucleus ofanatom process inwhichthe Identify Determine during alpha decay. the alphaparticlegivenoff off duringbetadecayand beta particlethatisgiven Reading Essentials What isthe Circle the 149 Picture This 4. 3. 150 a form? can daughter product isotope beforethe happen totheparent Interpret Explain half-life. daughter materialineach color theamountof Highlight withanother after eachhalf-life. parent materialremaining one colortheamountof Clues toEarth’sPast What hasto Highlight with availability in a certain rock.availability inacertain andits choose anisotope to lookforbasedonits half-life, scientists To dating, doradiometric theparent. half-life of isotope to the product and knowing daughter inamineral parent of rock theratio by measuring absolute ageof aetiooet ea oisduhe rdc.The the parent isotope to decay to product. itsdaughter of timeforonehalf of ittakes period acertain rate, onitsdecay Based productits daughter rate. ata certain Each parent isotope decays to productdaughter isformed. R therock. tothis information figure outtheabsolute ageof Scientistscanuse product daughter increases. the amountof parent isotope inarock decreases and theamountof passes, As time timethathaspassedsince rocks have formed. of What isahalf-life? Radiometric Ages isotope remains thatitisnotmeasurable. amount of such asmall After many half-lives, remain. atoms will carbon-14 theoriginal of onefourth after two half-lives, So, remaining decay thenext atoms 5,730years. will during the Onlyhalf Butwon’t. they decay into nitrogen-14 atoms. alltheremaining atoms will carbon-14 another 5,730years, You thinkthatin might change into nitrogen-14 atoms. atoms to thecarbon-14 of it So, takewill 5,730years forhalf is5,730years. carbon-14 lifeof thehalf For example, theparent decays material to product. thedaughter of half isotope to decay. the atoms inthe of anisotope isthetimeittakes forhalf of adio nrdociedcy h aetiooebek on The theparent isotope breaks down. In radioactive decay, ea fradioactive isotopes islike aclockkeeping track Decay of h gr eo hw o uigec aflf,one The figure below shows how each half-life, during me m P a a teri ren t r ic al t dat 2 1 2 1 1 h ing lif a e lf - is theprocess usedto calculate the 4 1 4 3 2 h liv a es lf - 8 8 7 1 3 liv h a es lf - 1 1 1 6 5 4 h liv a es lf - % half-lif e

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. U uniformitarianism. He of used theprinciple much older. Scottish scientistJames Hutton to estimated be Earth But inthe1700s, wasonlyafewthousand years old. Earth changed by heatandpressure. older than3.96billionyears probably were eroded or Rocks years isabout4.5 billion old. Scientists estimate Earth Theserocks are about3.96billionyears old. on Earth. came from. rocks they theoriginal these pieces onlygives theageof Dating thateroded from particles olderrocks. made upof Why? Many rocks are sedimentary can’t bedated thisway. rocks Most sedimentary rocks. andmetamorphic igneous or charcoal. wood, bones, age of candetermine the they inasample, carbon-14 amount of Once scientistsknow the isotope intheenvironment. ratio Scientists cancompare theisotope in thesampleto ratio the slowly thecarbon-14 decays. After theorganismdies, these two isotopes intheenvironment isalways thesame. of Theratio butsomeiscarbon-14. iscarbon-12, carbon the Most of from theenvironment to buildtheirbodies. organismstake Living incarbon up to 75,000years old. Uniformitarianism What aretheoldestknownrocks? Can radiometricdatingbeusedonallrocks? What doesradiocarbondatingshow? caused thedinosaursto become extinct. acomet have thatmight events such asthecollision of violent There are alsosudden, years. place over millionsof everyday processes thattake There are slow, change. of types rock layers anderode mountains. that ittook much longerthanafewthousandyears to form Hutton hypothesized just asslow allthrough Earth’s history. He were thatthey inferred landscape around himwere slow. today are similarto thosethatoccurred inthepast. nif eoerdoercdtn a sd many peoplethought datingwasused, Before radiometric datinghasbeenusedto dateRadiometric theoldestrocks dated areRocks usually thatcanberadiometrically andcharcoal wood, isusefulfordatingbones, Carbon-14 Today, scientists agree that Earth hasbeenshapedby two thatEarth scientistsagree Today, Hutton thattheprocesses observed that changed the o r mitar ianism states that Earth processesstates thatEarth occurring 5. 6. sedimentary rock? radiometric datingworkon have shapedEarth? two typesofchangethat Explain Describe Reading Essentials Why doesn’t What arethe 151 3. 2. 1. radioactive decay: half-life: absolute age: Mini Glossary 152 or why not. Was helpful?Explainwhy thisstrategy terms. In you vocabulary thissection highlighted over carbon-14 time. to showFill inthehalf-lifechart thedecay of between absolute ageandrelative age. Thenexplain thedifference Review theterms andtheirdeﬁnitionsintheMini Glossary. After You Read Section breaks down decay End of Clues toEarth’sPast time ittakesforhalfoftheatomsinanisotopeto age, inyears,ofarockorotherobject process inwhichthenucleusofanatom 3.125 11,460 6.25 0 5,730 12.5 Passed Years 100 Carbon-14 Percent Half-Life ofCarbon-14 ages ofrocks. games, andprojectstohelpyou learnmoreabouttheabsolute Visit uniformitarianism: radiometric dating: ﬂ7.msscience.com of theparent daughter productinamineralandknowingthehalf-life age ofrockbymeasuringtheratioparentisotopeto past occurring todayaresimilartothosethatoccurredinthe principle statingthatEarthprocesses process usedtocalculatetheabsolute to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chapter Earth’s Place in Space 00103 section ●1 Earth’s Motion and Seasons Benchmarks—SC.H.2.3.1: The student recognizes that patterns exist within and across systems. Also covers: SC.C.2.3.7; SC.E.1.3.1

Before You Read What You’ll Learn ■ about Earth’s shape and Every day the Sun rises and sets. Seasons change throughout physical properties the year. What causes these changes? Write your ideas below. ■ about Earth’s rotation and revolution ■ why Earth has seasons

Read to Learn Study Coach Outline As you read the text, Earth’s Physical Data outline the facts about Earth’s properties and how Earth moves Think about the last time you saw a sunset. The Sun through space. Use the headings seemed to be sinking lower and lower in the sky. Then it as part of your outline. disappeared. Maybe it looked like the Sun was actually moving. A long time ago, when people observed the sky, they thought the Sun and the Moon moved around Earth each day. But now it is known these objects seem to move because Earth is moving. What is Earth’s shape? Pictures from space show that Earth is shaped like a giant ball, or sphere (SFIHR). A sphere is a three-dimensional object whose surface at all points is the same distance from its center. Earth’s sphee shape is not perfect. It bulges slightly at the equator and is somewhat ﬂattened around the poles ●A Organize Information Make the following six-tab What is the evidence of Earth’s shape? Foldable to help you organize information about Earth’s Have you ever stood on a dock and watched a sailboat motion. come in? If so, you may have noticed that the ﬁrst thing you see is the top of the boat’s sail. This occurs because Earth’s Earth’s Orbit curved shape hides the rest of the boat from view until it is Earth’s

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Seasons Earth’s closer to you. As the boat slowly comes closer to you, more Tilt Earth’s and more of its sail is visible. Finally, the entire boat is in Solstices Earth’s view. This is proof that Earth is a sphere. Equinoxes Place in Space

Reading Essentials 153 2. 1. 154 your work. than atthepoles.Show diameter isattheequator much fartheracrossEarth’s table todeterminehow Interpret Data into asphere? What forceshapedEarth Draw Conclusions Applying Math Earth’s PlaceinSpace Use the fteojc,gvn ttesaeo aball. ittheshapeof giving theobject, of Particles are to pulled thecenter increase. pull gravitational itsmassand astheobjectgrows larger, However, anycollide shape. andsticktogether without particular particles At ﬁrst, how formed. they are becauseof spherical pull. thestronger itsgravitational larger anobjectis, The pullbetween themisweak. thegravitational are apart, force allobjectsto thatattracts daee) n te rpriso at.Sm fthese thetablebelow. Someof areproperties in shown Earth. of andotherproperties (diameter), Earth thedistance through the center of (circumference), How doesgravity affectEarth’s shape? What aresomeofEarth’s physical properties? ag bet nsae uha lnt n on,often such asplanetsandmoons, inspace, Large objects isa Gravity Earth’s shapeiscausedby spherical gravity. Scientists have measured thedistance around Earth vrg est 5.52g/cm Average density oa a 24h 365 days,6h,9min (path aroundtheSun) Period ofrevolution(1year) 149,600,000km 23h,56min Solar day Period ofrotationrelativetostars(1day) 40,075 km Average distancefromtheSun 40,008 km (average massperunitvolume) 12,756km Mass 5.98 12,714km (distance aroundEarthattheequator) Circumference (equator) (distance aroundEarththroughNandSpoles) Circumference (poles) Diameter (equator) Diameter (poletopole) ofEarth Physical Properties

adec te.When objects ward each other. 10 24 3 kg

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. what causesyou to experience day andnight. R alsomoves Earth alongapatharound theSun. each day, line. spinsaround thisimaginary Earth pole. south geographic to the polethrough Earth geographic fromdrawn thenorth The Earth’s axis. and southendsof Earth’s polesare located geographic atthenorth figure above. appear to move from east to west? Theanswer inthe isshown set each day orwhy theMoon andotherobjectsinthesky the distance around thepoles. causes thedistance around theequator to begreater than This equator andissomewhatflattened arouond thepoles. What isEarth’s revolution? Motions ofEarth aperfectsphere? Is Earth the Sun inthefigure isshown above. Earth’s revolution around theSun. complete revolution of rotates onitsaxisapproximately one 365times during soEarth aboutoneyear toEarth travel around theSun, e at a nte yeo oin As itspins onitsaxis motion. of hasanothertype Earth Have you ever wondered why theSun and appearsto rise atthe It bulgesslightly isnotaperfectsphere. Earth v ol R u otat t io n io stemto fErhaon h u.It takes around theSun. Earth is themotionof n stesinn fErho t xs Thisis onitsaxis. Earth is thespinningof axis (orbit) 365days Revolution is an imaginary line is animaginary 4 1 24 hours Rotation S Axis N Picture This 3. 4 . around theSun? complete onerevolution does ittakeforEarthto Illustrations Interpret Scientific one revolution? it takesEarthtocomplete Earth completeinthetime How manyrotationsdoes Draw Conclusions Reading Essentials How long 155 Picture This 6. 5. 156 have seasons? Infer Explain southern hemisphere? what seasonisitinthe the northernhemisphere, Earth’s PlaceinSpace When itiswinterin Why doesEarth eouinec er Earth’s revolution each year. completing one alsomoves Earth around theSun, night. What causesthesechanges? increases. gradually daylight hours andthenumber of the weather iswarmer, When comes, spring Sun remains intheskylater each day. temperatures are colder winter. during andthe There are fewer daylight hours, surface. Less reaches direct sunlight the the Sun atalower angle. thehemisphere strikes Sunlight tilted away from happens. theopposite In winter, more heat. bring andthey direct, TheSun’s rays are more thesummer. during angle higher thehemisphere strikes tiltedsunlight toward theSun ata Also, theplanethaslongerdaylight hours. of that half When Earth’s hemisphere istilted toward northern theSun, daylight hoursthanthehemisphere that istilted away. anotherpart. the Sun during hemisphere istilted toward theSun andtilted away from thenorthern Earth’s orbit, of shows part thatduring Thefigure below thetiltisabout23.5degrees. of angle specific places on Earth receivespecific places onEarth varies. that energy theamountof However, throughout theyear. receives Earth energy from theSun doesnotchange much But thetotal amountof from itinJuly. andfarther January oroval shape. anellipse, forms the Sun, How doesEarth’s orbitrelatetoseasons? How doesEarth’s tiltcauseseasons? You earlierthatEarth’s learned rotation causesday and you notice thatthe As theweeks pass, A newyear begins. The hemisphere thatistilted toward theSun hasmore The hasseasonsbecauseitistilted onitsaxis. Earth Earth’s causesitto becloserto ellipticalorbit theSun in hemisphere for northern Summer o r bit , or curved patharoundor curved hemisphere for northern Winter

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. The dates forsolstices andequinoxes change over time. equinox Thefall isSeptember 21or22. is March 21or22. equinox spring In hemisphere, thenorthern the figure above. You canseethisin neither toward noraway from theSun. Earth’s tiltis equinox, During overequal all theworld. day are nearly andnight andthelengthsof Earth’s equator, other thanEarth. theMoon andplanets Later aboutmotionof you learn will tilt andrevolution around theSun causeseasonsto occur. Earth’s theSun andsetinthesky. appearsto rise its axis, The solstice. Twice ayear there isa relative to Earth’s equator changes. What isEarth’s placeinspace? What causesequinoxes? What causesthesolstices? figure below. solsticethe winter isinJune Thesoltices are inthe shown thesummersolstice isinDecember; hemisphere, southern In the whentheSun islowest atnoon. December 21or22, Winter hemisphere on solstice happensinthenorthern intheskyatnoon. whentheSun ishighest June 21or22, soltices.winter Thesetimesare asthesummerand known Capricorn. Cancer orthetropic of directly over theTropic of andis theequator, greatest orsouthof distance north Earth is shaped much like a sphere. As Earth rotates As Earth on much isshaped likeEarth asphere. At an theSun’s position Earth’s axis, thetiltof Because of ntenrhr eipee summer solstice happenson hemisphere, In thenorthern e q uino solst x hemisphere for northern Summer solstice E whnhs,theSun is directly above (EE kwuhnahks), ic e is thetimewhenSun reaches its equinox Autumn equinox Spring Cancer Tropic of Capricorn Tropic of Equator Winter solstice for northern hemisphere Picture This 7. 8. solstice, whenisitlowest? at noonduringthesummer the Sunishighestinsky begins intheUnitedStates. shadows whenwinter figure ofearththat Draw Conclusions Illustrations Interpret Scientific Reading Essentials Circle the 157 If Mini Glossary 3. 2. 1. orbit: equinox (EEkwuhnahks): axis: 158 it moves? What didyou useto otherstrategies helpyou read andunderstandthissection? your Did outlinehelpyou andhow understandmore aboutEarth moves through space. you outlinedthefa As you read thissection, Complete thesentences to compare andcontrast Earth’s revolution and rotation. terms thatare related asentence andwrite usingbothterms. the Choosetwo of above. Review theterms andtheirdefinitionsintheMini Glossary After You Read Section hours ofdayandnight Sun isdirectlyaboveEarth’sequatorandthereareequal geographic pole the northgeographicpolethroughEarthtosouth h Sun the End of imaginary linearoundwhichEarthspins;drawnfrom Earth revolvesaroundthe______. Earth rotatesonits______. a curvedpathfollowedbyEarthasitmovesaround Earth’s PlaceinSpace twice-yearly timewhenthe Earth’s ______takesdays. Earth’s ______takeshours. cts aboutEarth’s andhow properties Earth solstice: rotation: revolution: motion andseasons. games, andprojectstohelpyou learnmoreaboutEarth’s Visit which causesdayandnight north orsouthofEarth’sequator takes about365 fl7.msscience.com time whentheSunreachesitsgreatestdistance the spinningofEarthonitsaxisevery24hours, the motionofEartharoundSun,which – 4 1 days, oroneyear,tocomplete to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. highlands. They are They about4.6billionyears old. highlands. oldest moonrocks analyzed sofarwere foundinthelunar The areThey several thanthemaria. kilometers higher the Moon sofar. are They theyoungest rocks foundon 3.7 billionyears old. Therocks were to about3.2billion analyzed onEarth. Theserocks were collected moonrocks from themaria. the During history. These depressions may have earlyintheMoon’s formed bowl-like ontheMoon’s regions surface. flowed into large, theoceans. remindedthey Galileoof dark-colored areas Galileonamedthe areasdark are (MAReeuh). maria The andlight-coloreddark- areas ontheMoon’s surface. you cansee you usebinocularsoratelescope, If full moon. What arelunarhighlands? What aremaria? The Moon’s SurfaceandInterior about theMoon? you Listwhat know below. What doyou know inspace. and isourclosestneighbor Earth It orbits The Moon isEarth’s satellite. onlynatural section The light-colored areas ontheMoon are lunarhighlands. Maria probably whenlava formed from insidetheMoon youSuppose thatonaclearnight take agoodlookatthe chapter Read toLearn Before You Read 00 10 3 Also covers: satellites. Benchmarks—SC.E.1.3.1 AnnuallyAssessed: ● 2 SC.H.1.3.1; SC.H.2.3.1 Earth’s PlaceinSpace Earth’s Moon maria, Apollo h ai odfrsa,because the Latinword forseas, onmsin,astronauts moon missions, The studentunderstandsthevastsizeofourSolarSystemandrelationshipplanetstheir answers. yourself untilyouknowallthe answer ontheotherside.Quiz side ofaflashcardandthe point. Writethequestiononone a quizquestionforeachmain Make Flash Cards 1. What You’llLearn ■ ■ ■ ■ Study Coach Identify found? oldest moonrocksbeen Moon about theoriginof the causesofeclipses phases about theMoon’s interior surface featuresand about theMoon’s Reading Essentials Where havethe Think of 159 Picture This 3. 2. 160 List Describe beginning withthecore. layers oftheMoon, in thefiguretolist craters ontheMoon. Earth’s PlaceinSpace Use theinformation what caused Moon’s crust rtr hr r nargo,theoldersurface is. craters there are inaregion, Themore or aplanet’s surface are compared to otherparts. amoon’s Craters of helpscientistsfindouthow oldparts lava allowing flows to fillinthelargedepressions. its crust, could cracks have in formed theMoon, meteorites struck When Meteorites are space objectsthatstrike thesurface. craters. with a radius of about 300–450 km. about300–450 of aradius with solidcore layer innermost The may beaniron-rich, down. mantlemay continue another500km softlayer A of down. which may extend 900km to 950kmfarther the mantle, Below isasolidlayer thecrust called thick onthefarside. andabout150km kmthickonthesidefacingEarth 60 in thefigure below. asshown theMoon’s hasbeendeveloped, interior model of a moonquakes, Basedonthestudy of measure moonquakes. are usedto seismographs OntheMoon, earthquake activity. are usedto theseinstruments measure OnEarth, vibrations. orseismic thatmeasures tremors, is aninstrument seismograph A ontheMoon. (SIZEmuh grafs) seismographs What arecraters? What istheinsideofMoonlike? syulo tteMo’ ufc etrs you see will As you lookattheMoon’s surface features, h rtlyro h oni h rs,which isabout theMoon isthecrust, The firstlayer of the During C r at e r Apollo s are depressions by formed largemeteorites. The Moon’s Layers pc rga,astronauts leftseveral space program, Rigid mantle Non-rigid mantle Core

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. ftewsensd fteMo,te itemr fthe eastern side. thena littlemore of theMoon, thewestern sideof of canfirst seealittlemore observers the Moon’sduring orbit, So Moon are a27.3-day notexactly thesame during period. the meanstherotation This andrevolution of away. farther anditmoves slower whenitis itmoves faster, to Earth, below. intheillustration asshown facing Earth, theMoon isalways thesamesideof time, same amountof theMoon take the Becausethesetwo motionsof on itsaxis. TheMoon alsotakes 27.3days to rotate once around Earth. It takes 27.3days fortheMoon to complete oneorbit Earth. theMoon always faces Earth. same sideof Read Earth? ontoon itsaxisasitorbits explore why the DoesthismeanthattheMoon doesn’t spin same positions. You’ll features anddark stay inthe seethatitsbright row. prove thisby lookingattheMoon ina forseveral nights fromejected Earth’s mantleandcrust. that theMoon may have mostlyfrom formed material theidea Thissupports density. the mantleandcrust—in TheMoon ismostlike Earth’s outer two layers— volume. theMoon’s core compared issmall to itstotalHowever, What aretheMoon’s cycles? Motions oftheMoon How istheMoonlike Earth? h onsobti nelpe When theMoon iscloser The Moon’s isanellipse. orbit 384,000kmfrom The Moon isanaverage distance of You can theMoon always faces Earth. The samesideof iron core. alsohasadense, Earth Like theMoon, The Moon’sorbit pole North Picture This 4. 5. figure alwaysfacingEarth? lunar landershowninthe Earth indensity? the Moonaremostlike Identify Observe Reading Essentials What layersof Why isthe 161 Picture This 7. 6. 162 of theMoon. lighted sideofeachfigure the Moon? Identify Explain Earth’s PlaceinSpace Why canwesee Highlight the change intheway theMoon looksto onEarth. anobserver Thesemotionscausetheregular cycle of around Earth. thattheMoonlearned rotates onitsaxisandrevolves You notice how andpositionintheskychange. itsshape Earth, half of that side is lighted. This phaseisfirstquarter. This (GIHbus). The next phase iscalledwaxinggibbous that sideislighted. of half Earth, As theMoon continues around itstrip waxing crescent. phaseiscalled This sliver islighted. onthesidefacingEarth thin a About 24hoursafter newmoon, growing insize. or phasesare The saidto bewaxing, islighted. facing Earth Moon isfacingtheSun. the of You can’t half seeanewmoonbecausethelighted moon occurs whentheMoon andtheSun. isbetween Earth the moon. What you seeare phasesof part. thelighted of even less, or you Sometimes justseehalf, theMoon. of part lighted you don’t always seetheentire However, theMoon. of theSun always onehalf lights Moon revolves around Earth, seen from Earth. What causestheMoon’s phases? When istheMoonwaxing? What isthenew moon? How doestheSunlightMoon? fyuwthteMo o eea asi o,you may you watch theMoon forseveral days inarow, If hrl fe h e on oeadmr ftheside more andmore of after thenewmoon, Shortly New The Moon phasesare inthefigure illustrated below. As the You seetheMoon becauseitreflects sunlight. Full M gibbous gibbous Waning Waxing o o n p hases 1st qtr. 3rd qtr. Earth r h hnigveso theMoon as of are views thechanging crescent crescent Waning Waxing New Sunlight

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. in thefigure below. time difference between theMoon’s phasesandrevolution You canseethe andtheSunbetween atnewmoon. Earth again the Moon abouttwo days itself longerto align It takes revolution around theSun causethetimedifference. Earth’s 27.3days to revolve once around Earth. only you recall thattheMoon will takes However, days. 29.5 again. the newmoon Moon The continues to waneuntilitistimefor new moon. thefinalphasebefore thenext followed by waningcrescent, is This islighted. thesidefacingEarth of when onlyhalf Next comes third quarter, takes place justafter fullmoon. to decrease. begins thatislighted Earth the Moon. isbetween theSun and Earth At fullMoon, phase. gibbous It comes after thewaxing islighted. thefacingEarth of all when Thisisthefullmoon, looks like acomplete circle. Moon’s phasesandrevolution? What isthetimedifferencebetween the When istheMoonwaning? What isthefullMoon? moon h opeecceo theMoon’s phasestakes about The complete cycle of Waning gibbous Now thephasesare saidto bewaning. thesidefacing theamountof After passingfullmoon, it whenyou lookattheMoon from Earth, Sometimes, Full 14 Day 4 3 New moon Earth’s orbit Day 29 again New moon Day 1 2 1 2 days once againaligned. Earth, Moon,and distant starare Day 27 Sun 3 1 Picture This 8. after waningcresents. circle thephasethatcomes Identify Distant star Reading Essentials On thefigure, 163 eclipses. ideas aboutsolarandlunar to helpyouidentifythemain the followingtwo-tabFoldable Picture This ● B 9. 164 Find MainIdeas the Moon’sshadow. umbra, ordarkestpartof of EarthintheMoon’s Identify Earth’s PlaceinSpace eclipse eclipse lunar solar Circle thearea Make ri.Thismostoften causestheMoon’s shadow to missEarth. orbit. because theMoon’s from istilted Earth’s atanangle orbit Eclipseshappenonlyafewtimeseach year lined upperfectly. canoccur. eclipses ways, When shadows are castinthese Moon afullmoon. during alsocancast itsshadow onto Earth the its shadow onEarth. oto fErhssrae uignwmo,a newmoon, During Earth’s surface. of portion Eclipses avoid harming your eyes, never lookdirectly eclipse. atasolar never avoid youreyes, harming only afewminutes inany onelocation. asolareclipselasts and theMoon initsorbit, ismoving rotates BecauseEarth have solareclipse. apartial shadow, seen easily. Theskybecomes andstars canbe dark a total solareclipse. experience itsshadow, of or thedarkest part Moon’s umbra, inthe Onlyareas onEarth Earth’s surface. reaching of part It shows how theMoon from blockssunlight figure below. Lookatthe moves Earth into theMoon’s shadow. occurs if What isasolareclipse? Eclipses occur only when the Sun, the Moon, and Earth are andEarth theMoon, Eclipses occur onlywhentheSun, itcancast When theMoon theSun, linesupdirectly with Sometimes theMoon from blockssunlight reaching a ra htaei h euba rlgtrpr fthe of part or lighter Areas thatare inthepenumbra, Sunlight Moon Umbra Penumbra WARNING: To Earth solar e c lipse

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. mantle andcrust. Earth’s similar to thatwould material have beenthrown off TheMoon’s is density the Moon have different densities. isstrengthened and bycollision thefactthatEarth theory The coulddebris have condensed to theMoon. form thegasand Within about1,000 years, aroundorbit Earth. would have gasanddebris beenthrown into amounts of Large through Earth’s andplungedtoward crust the core. Such anobjectwould have broken Earth. collided with aMars-sized space objectmay have 100 millionyears old, When wasabout Earth thecollisionto hypothesis. support What isthecollisionhypothesis? Origin oftheMoon What isalunareclipse? through Earth’s umbra, a partial lunareclipseoccurs. apartial through Earth’s umbra, When theMoon passespartly across theMoon’s surface. move Earth you shadow canseethecurved of shadow, or lighter andinto theumbra thepenumbra, moves outof As theMoon through Earth’s atmosphere. orbends, refracts, Moon appearsto bedeepred becausesomesunlight total lunareclipseoccurs. a Earth’s shadow, When theMoon of isinthedarkest part from blockssunlight reaching Earth theMoon. shadow. fullmoonmoves The into Earth’s Moon are linedup. from material thrown off of a rapidly spinningEarth. rapidly a of from thrown material off Theﬁssionhypothesis states thattheMoon formed Earth. Then Earth’s captured theMoon gravity asitpassedcloseto Moon atdifferent formed locationsinthesolarsystem. andthe Earth According to thecapture hypothesis, material. thesame Moon atthesametimeandoutof formed theMoon. of to explain theorigin h olcinadsuyo moonrocks brought evidence The collection andstudy of Before the A uigattllnrelpe h ulmo akn.The thefullmoondarkens. atotal lunareclipse, During The co-formation hypothesis states that Earth andthe The co-formation hypothesis states thatEarth l unar e c lipse Apollo cuswe h u,Erh andthe Earth, occurs whentheSun, pc rga,scientistshadhypotheses space program, 10. 11. orbit aroundEarth? and debristhrowninto the Moonformedfromgas of theMoonsuggeststhat hypothesis abouttheorigin longer thanasolareclipse? think alunareclipselasts Contrast Compare and Identify Reading Essentials Which Why doyou 165 After You Read Mini Glossary crater: depression formed by impact of meteorites or comets; moon phase: changing view of the Moon as seen from the more craters in a region, the older the surface Earth, which is caused by the Moon’s revolution around lunar eclipse: occurs during a full moon when the Sun, the Earth Moon, and Earth line up in such a way that the Moon solar eclipse: occurs during a new moon when the Sun, the moves into Earth’s shadow Moon, and Earth are lined up in a speciﬁc way and Earth moves into the Moon’s shadow

1. Review the terms and their deﬁnitions in the Mini Glossary. Choose a term and write a deﬁnition of the term in your own words.

2. Complete the concept map to name the four major phases of the Moon.

______

Quarter

______EARTH New Moon Moon

______

Quarter

3. Think about what you learned. How did making ﬂash cards help you? Describe another study strategy you could use for this section. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

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166 Earth’s Place in Space Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. The or1 AU. This distance isreferred to asoneastronomical unit, isabout150,000,000kmfrom theSun. forexample, Earth, to itisnotpractical usekilometers. distances are sohuge, isbecausethe This notkilometers. astronomical units, something thislarge?Distances inspace are measured by How would you andother measure theSun. objects thatorbit comets, asteroids, planets, theSun, made upof forms of energy foundinoursolar system. energy of forms Other galaxiesexist and have thesameforces and gives off. it light andaboutaveragemiddle-aged intheamountof Sun The is Milkystars inourgalaxy—the Way galaxy. billionsof TheSun isone of like many otherstars. much fallmatter inthesolarsystem iscontained intheSun. of More than99percent by fusinghydrogen into heliuminitscore. gasthatproduces energy TheSun ball of isanenormous Sun. measure thelarger distances between thestars. Otherunitsare used to AU from theSun. is more than5 thelargestplanetinsolarsystem, Jupiter, the solarsystem. What kindofstaristheSun? Size oftheSolarSystem List thembelow. theplanetscanyou name? How many of theSun. also orbit otherplanets Eight isthethird planetfromEarth theSun. section lhuhteSni motn olf nErh itis to theSun lifeonEarth, isimportant Although Our Our solarsystem isextremely large. ttecne fthesolarsystem isastaryou know asthe At thecenter of chapter Read toLearn Before You Read 00 a 10 st 3 Also covers: satellites. Benchmarks—SC.E.1.3.1 AnnuallyAssessed: r o no mical unit ● 3 SC.D.1.3.5; SC.E.1.3.2;SC.E.1.3.3;SC.E.1.3.4;SC.E.2.3.1;SC.H.1.3.6;SC.H.2.3.1;SC.H.3.3.5 Earth’s PlaceinSpace Earth andtheSolarSystem , is aunitusedto measure distances in The studentunderstandsthevastsizeofourSolarSystemandrelationshipplanetstheir solar sy st e m is correctly. answer yourownquestion ﬁnished reading,seeifyoucan for eachsubject.Whenyouhave the text,createaquizquestion and outerplanets. and contrasttheinnerplanets Foldable tohelpyoucompare Make thefollowingtwo-tab ● Create-a-Quiz C What You’llLearn ■ ■ ■ Compare andContrast Study Coach of outerplanets about thecharacteristics contrast withEarth planets compareand about howotherinner of innerplanets about thecharacteristics Reading Essentials As youread 167 SC.E.1.3.1 ✔ FC Picture This A

T 1.

168

F F

O O

ﬁgure. what youcanseeinthis outer planetsbasedon Compare

2. planets. names offourinner C C

U U S S List Benchmark Check Annually Assessed Earth’s PlaceinSpace Write the the innerand ml c/okpae htsest eoto place. a smallice/rock planetthatseemsto beoutof Oneis theseare asgasgiants. known Four of asteroid belt. outer planets. have thinatmospheres compared to theatmospheres of They Theinnerplanetsare mostlysolidandrocky. below. theasteroid intheﬁgure beltasshown of inside theorbit Inner planetshave thatlie orbits planets orouter planets. mi imtr Mercury hasalmostnoatmosphere. 2 kmindiameter. Theplanetseemsto have about shrunk tocrust shrink. causingtheouter solid iron-rich core cooled andcontracted, These cliffsmay have whenMercury’s formed molten, which are 3kmhigh. someof Mercury hascliffs, surface of The into whenmeteorites crashed craters itssurface. formed rock. andare madeupmainlyof Earth word after theLatin are planets, They astheterrestrial known The Planets What is Inner Planets ue lnt aeobt htleotieteobto the Outer planetshave of thatlieoutsidetheorbit orbits The planetsinoursolarsystem canbeclassiﬁedasinner h lss lntt h u sMruy It iscovered by The closestplanetto theSun isMercury. andMars. Earth, Venus, The innerplanetsare Mercury, terra Mercury erh.Theinnerplanetsare similarinsize to (earth). like? . . 5.2 2.7 1.5 0 Sun Asteroid belt Mars Astronomical units Jupiter

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. h oa ytm lmu os isfoundonMars. Mons, Olympus the solarsystem, Thelargestvolcano in Mars inthefigure isshown below. thesurface of of Asection volcanic rocks foundonEarth. Theserocks are similarto some planet areddish color. gives This the is foundinweathered surface rocks onMars. foundinrust, thematerial Iron oxide, called thered planet. radiation. ultraviolet This ozone protects from theSun’s lifeonEarth harmful Earth’s atmosphere asthestratosphere. known the layer of exists in three oxygen atoms boundtogether, a molecule of Ozone, andgas. liquid, inthree states—solid, exist because temperatures onEarth’s surface allow water to in agreenhouse. process The issimilarto what occurs to reach about472°C. from theSun causingthesurface temperature ontheplanet Thickcloudssurround Venus energy andtrap Earth. that of Venus different from isvery theatmosphere of However, It isoften referred to asEarth’s twin. and massto Earth. Dr. TimothyParker,JPL like?What isMars like? What isplanetEarth What is h orhinrpae rmteSni as It isoften innerplanetfrom theSunThe fourth isMars. It isunique The third planetfrom theSun isEarth. issimilarinsize Venus, The second planetfrom theSun, Venus like? Picture This 3. 4. surface ofMarslooklike? Explain Describe unique. surface temperaturesare Reading Essentials why Earth’s What doesthe 169 5. 6. 170 largest stormonJupiter? called theringedplanet? Explain Identify Earth’s PlaceinSpace Why isSaturn What isthe topeeo Earth. atmosphere of ismuch thinnerthanthe somenitrogen andargon, with dioxide carbon upmostlyof made Mars, The atmosphere of have by beencarved water flowing sometimeinthepast. andsummer.in size winter between Martian Theseice capschange frozen dioxide. carbon by alayer of next page. andcanbeseeninthefigure onthe ice androck, pieces of are madeupof Therings divisions. itsseven majorring of isoften planetbecause Saturn calledtheringed helium. hydrogen and Saturn’s atmosphere are madeupmostlyof life. and search of forsigns spacecraft in2008tolaunch study anorbiting thismoon Space Administration (NASA) ispreparing amissionto life may exist onEuropa? TheNational Aeronautics and Doesthatmean beneath theice onthemoonEuropa. crust to liquidwater exist isthought An ocean of solar system. The moonIo isthemostvolcanically active body inthe whodiscovered themin1610. satellites after GalileoGalilei, are They calledtheGalilean andCallisto. Ganymede, Europa, Jupiter are Io, fourlargestmoonsof The system. than 300years. formore hasraged theGreat Red Spot, The largeststorm, hydrogen andheliumhasmany huge storms. mostly of Its atmosphere ismade and rotates sixdays. once every It isthefifthplanetfrom theSun Earth. of thewidth twice elementssuch ashydrogen light andhelium. made upof are They mainly denseatmospheres. planetswith giant are they allgaseous Except forPluto, andPluto. Neptune, Is therewater onMars? What is Saturn like?What isSaturn What isJupiterlike? Outer Planets There are long channels on Mars. These channels These may There are longchannels onMars. frozen water covered Mars hastwo polarice capsmadeof The sixth planet from the Sun is Saturn. The gasesin The The sixthplanetfrom theSun isSaturn. Jupiter islike aminiature solar With its63moons, isabout Jupiter, The largestplanetinthesolarsystem, Uranus, Saturn, The five outer planetsare Jupiter,

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. rising to form a temporary atmosphere. to a temporary form rising thaw these materials andbecome gases is closestto theSun, But when Pluto monoxide sometimescovers and carbon Pluto’s surface. nitrogen, methane, frozen A layer of rock. of ice andpartly of to It bemadepartly isthought 1930. onerevolution since itsdiscovery in than 20percent of Triton isfairlyyoung. craters on Triton’s surface suggests thatthesurface of lack of thatshoot hasgeysers gase Triton, largestmoon, The moonshaveThirteen beendiscovered. any on faster thanwinds exceed 2,400km/h, Neptune Winds of inthegaseousportion its bluishcolor. Earth. rocky core aboutthesize of may surround acentral, Theicylayer change into anicysolidtoward theinterior. to isthought Thismaterial water andothermelted ices. Thislayer of iscomprised partially into aslushlike layer. changes andmethane gradually helium, hydrogen, phere of Uranus to have isthought 27moons. color. theplanetabluish-green giving red light absorbs Methane reflects and bluelight helium andmethane. alsocontains hydrogen, upmostlyof made atmosphere, before oxygenEarth gas. becameamajoratmospheric The environment onTitan besimilarto thaton might orMars. Earth atmosphere denserthantheatmospheres of How isPlutodifferentfromother planets? What isNeptunelike? What isUranuslike? Pluto issofarfrom theSun thatithascompleted less themethaneinNeptune’s atmosphere gives Uranus, As with Its atmos- planetfromThe eighth theSun isNeptune. Its Uranus istheseventh planetfrom theSun. hasan Titan, Thelargest, hasatleast33moons. Saturn uie Saturn Jupiter u irgnit pc.A ous nitrogen into space. other planet. Picture This 7. 8. these twofigures? and Saturnyoucanseein difference betweenJupiter Uranus abluishcolor? Observe Explain Reading Essentials What gives What isthe 171 Picture This 10. 9. 172 what willitbecalled? the picturefallstoEarth, Identify discover Charon? Why didittakesolongto Draw Conclusions Earth’s PlaceinSpace If themetorin after Pluto. years Charon wasdiscovered nearly50 this, Because of usually can’t bedetected usingground-based telescopes. Charon issocloseto Pluto thatit covered by water ice. and meteoroids. Does Plutohave aMoon? Other ObjectsintheSolarSystem they arethey calledmeteorites. fallto they Earth, If are they calledmeteors. atmosphere, meteoroids enter Earth’s If asmeteoroids. known these processes produce smallobjectsinthesolarsystem Bothof smallpieces break off. When asteroids collide, orbit. beyond Pluto’s orbit. Cloudislocated far andtheOort beyond Neptune’s orbit, TheKuiper Beltislocated Kuiper Cloud. BeltandtheOort thesolarsystem’s comets are located inthe Almost allof Comet tailsalways pointaway from theSun. figure below. inthe isshown itstail, with Acomet, tails. vapor andform comets to turn of parts approachAs theirorbits theSun, material intheasteroidmaterial belt. probably kept aplanetfromgravity from forming the Jupiter’s tremendous separates theinnerandouter planets. asteroid beltisusedby astronomers linethat asadividing The most often foundinabeltbetween Mars andJupiter. h ufc fCao,Puosmo,appearsto be Pluto’s moon, Charon, The surface of te bet nteslrsse r seod,comets, Other objectsinthesolarsystem are asteroids, When comets break up, some of the particles remain in theparticles of some When comets break up, C o me ts are made mainly of rocky particles andwater rocky ice. particles are mademainlyof A st e r o ids r ml,rocky objectsthatare are small,

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. system is thought tosystem have isthought inthefigures formed below. Ypucanseehow thesolar over cloud. from theoriginal left material Comets to are bemadeupof thought planets. gaseous giant, cloud were better of fortheformation the Conditions of intheouter part solid planetsto form. inthesolarsystem. andotherobjects moons, planets, the formed Thismaterial andstucktogether. collided, thenebulacondensed, anddust intheouter areas of ice, thegas, Therest of toward thecenter to anearlySun. form rotating faster andflattened into adisk. itstarted As itcondensed, or pullingtogether. condensing, have might causedthecloudto start explodingnearby star, from perhaps a Shockwaves, rotating slowly inspace. This large years anddustabout5billion ago. ice, gas, large cloudof the Sun from andalltheplanetsotherobjectsformed a How mighttheplanetshave formed? Origin oftheSolarSystem odtosi h ne ato thecloudcausedsmall, of Conditions intheinnerpart thecondensing waspulledby material gravity Most of How Onehypothesis didthesolarsystem isthat begin? ne b Formation oftheSolarSystem ula NByhlh,o lu fmtra,was material, orcloudof (NEB yuhluh), Picture This 11. 12. part? conditions intheouter of theclouddifferfrom conditions intheinnerpart bottom diagram the stageshownin diagram isdifferentfrom system showninthetop how thestageofsolar Contrast Compare and Illustrations Interpret Scientific Reading Essentials How did Describe 173 After You Read Mini Glossary asteroid: small, rocky object found in the asteroid belt comet: space object made of rocky particles and ice that between the orbits of Jupiter and Mars forms a tail when orbiting near the Sun astronomical unit: unit used to measure distances in the nebula: cloud of gas and dust particles in interstellar space solar system; 1 AU equals 150,000,000 km solar system: the sun, planets, asteroids, comets, and other objects in orbit around the Sun

1. Review the terms and their deﬁnitions in the Mini Glossary above. Then write a sentence comparing two of the objects described.

2. Complete the concept map to show the formation of the solar system.

______

condensed ______Nebula into System Sun

______Comets

3. As you read this section, you wrote a quiz question for each subject. After reading, could you answer your questions? If not, did you go back and review the part of the section that you did not understand? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

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174 Earth’s Place in Space Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. is agelatinlike called material carry foodandwater throughout theplant. carry Thesecells long andhollow andhave attheirends. openings Somecells inplantstems are blood cells canchange shape. Muscle cells andsome cellA nerve cannotchange itsshape. can ﬁtinsideonered bloodcell. thesmallestbacteria isevenbacterium smaller—8,000of A A human blood cell ismuch smallerthantheeggcell. human A eggcell isnobiggerthanthedotonthis long. cell Anerve inyour legcould beameter from othercells. has many thatsendandreceive branches messagesto and cell A nerve tell youmight somethingabout its function. an outer covering calleda Allcells have lifefunctions. smallest unitthatcanperform fthecell. of Cytoplasm thatcontrols material contains hereditary thelife How docellsdiffer? Common CellTraits how thesepeoplework together to provide foodto customers. Thenexplain thosejobsonthelinesbelow. List three of Think aboutthedifferent have jobspeople inarestaurant. section A cell’s shapemay tell you somethingaboutits function. Acell’s shape Cells come indifferent sizes andshapes. Acell isthe cellsLiving have many incommon. things chapter Read toLearn Before You Read 11 3 Also covers: within thecell; Benchmarks—SC.F.1.3.2: of structuralorganizationforfunctioninlivingthings…; ● SC.H.1.3.4; SC.H.1.3.5;SC.H.1.3.7;SC.H.2.3.1 1 SC.F.1.3.6: Cells Cell Structure The studentknowsthatthecellswithsimilarfunctionshavestructures. The studentknowsthatthestructuralbasisofmostorganismsiscell…; c e l l me cy t o mb plasm SC.F.1.3.5: r ane (SI tuhplazum). . The studentexplainshowthelifefunctionsoforganismsarerelatedtowhatoccurs Inside every cellInside every i . SC.F.1.3.4: you deﬁnethosewords. the partoftextthathelps do notunderstand.Highlight section, circleallthewordsyou Words Identify Important 1. The studentknowsthatthelevels ■ ■ ■ What You’llLearn Infer openings atbothends? plant stemshollowwith and organsystems about tissues,organs, nucleus inacell the importanceofa functions ofcellparts the namesand As youreadthe Reading Essentials Why arecellsin 175 Prokaryotic Cell Eukaryotic Cell y Nucleolus Cell Gel-like capsule Nucleus with membrane Cell wall hereditary Cell membrane material

Flagellum Hereditary Ribosomes material Organelles Ribosomes

Picture This 2. Identify Circle the names What types of cells are there? of the features that are the same in both types of cells. Scientists separate cells into two groups, as shown in the figure above. A prokaryotic (proh kayr ee YAH tihk) cell does not have membrane-bound structures inside the cell. A cell with membrane-bound structures inside the cell is called a eukaryotic (yew kayr ee YAH tihk) cell. Cell Organization Just as restaurant workers have specific jobs, each cell in your body has a certain job to do. Cells take in nutrients, release and store chemicals, and break down substances Inc. w-Hill Companies, 24 hours a day. What protects a cell and gives it shape? A cell wall is a tough, rigid outer covering that protects the cell and gives it shape. The cell wall is outside the cell membrane. Cells of plants, algae, fungi, and most bacteria are each enclosed in a cell wall. A plant cell wall is mostly made up of a substance called cellulose. The long, threadlike fibers of cellulose form a 3. List three things found in the cell wall of a plant. thick mesh. The mesh allows water and dissolved materials to pass through the cell wall. Cell walls may contain pectin, which is used to thicken jams and jellies. Cell walls also a division of The McGra © Glencoe/McGraw-Hill, Copyright contain lignin. Lignin is a compound that makes cell walls rigid. Plant cells responsible for support have large amounts of lignin in their walls.

176 Cells What is the function of the cell membrane? The protective layer around every cell is the cell membrane. The cell membrane controls what happens between a cell and its environment. Water and some food particles move freely into and out of a cell through the cell membrane. Waste products leave through the cell membrane. What is cytoplasm? Cytoplasm is a gelatinlike material in the cell. Many important chemical reactions occur within the cytoplasm. Cytoplasm has a framework called the cytoskeleton, which helps the cell keep or change its shape. The cytoskeleton helps some cells to move. The cytoskeleton is made up of thin, hollow tubes of protein and thin, solid protein ﬁbers. What are the functions of organelles? 4. Describe What is the cytoskeleton? Most of a cell’s life processes happen in the cytoplasm. Within the cytoplasm of eukaryotic cells are structures called organelles. Some organelles process energy. Others make materials needed by a cell or other cells. Some organelles move materials. Others store materials. Most organelles are surrounded by membranes. Why is the nucleus important? The nucleus (NEW klee us) directs all cell activities. The nucleus usually is the largest organelle in a cell. It is separated from the cytoplasm by a membrane. Materials enter and leave the nucleus through openings in the membrane. The nucleus contains DNA. DNA is a chemical that has the code w-Hill Companies, Inc. w-Hill Companies, F T OC for the cell’s structure and activities. A U C

S F Benchmark Check Which organelles process energy? Cells need energy to do their work. In plant cells, food SC.F.1.3.5 is made in green organelles called chloroplasts ✔ 5. Explain the (KLOR uh plasts). Chloroplasts contain chlorophyll function of the nucleus. (KLOR uh ﬁhl), which captures light energy that is used to make a sugar called glucose. Animal cells and some other cells do not have chloroplasts. Animals must get food from their environment. The energy in food is stored until it is released by organelles called mitochondria (mi tuh KAHN dree uh). Copyright © Glencoe/McGraw-Hill, a division of The McGra © Glencoe/McGraw-Hill, Copyright Mitochondria release energy by breaking down food into carbon dioxide and water. Some types of cells, such as muscle cells, are more active than other types of cells. These cells have large numbers of mitochondria.

Reading Essentials 177 What organelle makes proteins? Protein takes part is almost every cell activity. Cells make their own proteins on structures called ribosomes, which are shown below. Ribosomes are considered organelles, even though they are not membrane bound. Hereditary material in the nucleus tells ribosomes how, when, and in what order to make proteins. Ribosomes are made in the nucleolus (new klee OHL us) and move out into the cytoplasm. Some ribosomes are free-ﬂoating in the cytoplasm and some attach to the endoplasmic reticulum. 6. Identify Where are ribosomes made? Animal Cell

Rough endoplasmic Smooth endoplasmic reticulum (RER) reticulum (SER)

Ribosome Nucleus

Nucleolus

Mitochondrion Cell membrane Cytoskeleton

Free ribosome Golgi bodies Lysosome

Plant Cell Picture This Inc. w-Hill Companies, Central vacuole 7. Circle the Compare Chloroplast organelles that direct cell activities in each cell. Free ribosome Highlight the organelle that Cell wall of adjacent cell contains chlorophyll. Nucleus Smooth endoplasmic reticulum (SER) Nucleolus

Ribosome

Rough endoplasmic

reticulum (RER) a division of The McGra © Glencoe/McGraw-Hill, Copyright

Golgi bodies Mitochondrion

Cell wall Cell membrane

178 Cells Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. ras An organs. Tissues are organized into works to keep thetissuealive. smd po orhat reis en,andcapillaries. Organ systems work together to keep anorganismalive. veins, arteries, your heart, is madeupof Your cardiovascular system together to afunction. perform organsthatwork An organsystem isagroup of blood tissues. and tissue, nerve cardiac tissue, organ thatismadeupof isan your heart For example, tissuethatwork together. of cells grouped together to a doonejobform Similar work anddependsonothercells intheorganism. A cell inamany-celled itsown organismperforms organized. digestive chemicals destroy thecell’s contents. released The alysosome’s breaks membrane down. cell dies, When a leaking into anddestroying thecytoplasm thecell. lysosome’s stops membrane the digestive chemicals from The chemicals thathelpbreak inthecell. materials down organelle calledalysoso rtisaeue ihntecl rmvdoto acell. proteins thecell are ormoved usedwithin outof The thatmake Rough ERhasribosomes proteins. store energy. Smooth ERprocesses such materials aslipidsthat the cell. foldedmembranes in which canbeprocessed materials andmoved around inside of isaseries orER, TIHKyuhlum), rih From CelltoOrganism How doesacellrecycleitsmaterials? materials? store or What typesoforganellestransport What istheendoplasmicreticulum? tr ellrmtras uha ae,wse,andfood. wastes, such aswater, store cellular materials, Vacuoles Cells have spaces membrane-bound calledvacuoles. the cell andto thecell where are membrane they released. Vesicles deliver thecellular to materials areas inside vesicles. cellular and puttheminto materials called structures The ﬁgure below shows how amany-celled organismis An Active cells break andrecycle down materials. The The Golg e nd Cell o o i plasmic r r (GAWL jee) g an smd po two ormore different types is madeupof Tissue e t icul me (LIsuhsohm)contains digestive b um o dies (en duhPLAZmihk• sort proteinssort andother Organ Organism t iss ue . Each cell system Organ ● Picture This to worktogether. describe howcellsareorganized below. UsetheFoldableto three-tab Foldable,asshown A 8. Describe organization. the mostcomplexlevelof of organizationand5as Use 1asthesimplestlevel each labelonthediagram. number from1to5beside Sequence Reading Essentials

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Organ Make a Write a 179 3. 2. 1. Golgi (GAWLjee)bodies: endoplasmic reticulum(enduhPLAZmihk•rihTIHKyuh cytoplasm (SItuhplazum): chloroplast (KLORuhplast): cell wall: cell membrane: Mini Glossary 180 a. isfound. organelle write Beside each organellelisted below, many-celled organism. Complete below to thediagram show of theorganization asentence acell andwrite structure todescribes explain itsfunction. Choose oneterm that Review the terms andtheirdeﬁnitionsintheMini Glossary. b. c. After You Read Section called vesicles other cellularmaterialsandputthemintostructures be processedandmovedaroundinsidethecell and givesitshape food inplantcells controls whathappensbetweenacellanditsenvironment lum): every cellwherehereditarymaterialiscontained End of nucleus chloroplast golgi bodies golgi Cells a tough,rigidoutercoveringthatprotectsthecell a seriesoffoldedmembranesinwhichmaterialscan the protectivelayeraroundacell,which organelles thatsortproteinsand a greenorganellethatmakes gelatinlike materialinside Tissue ln,Animal, Plant, games, andprojectstohelpyou learnmoreaboutcellstructure. Visit tissue: ribosome: organelle: organ: kleeus): nucleus (NEW mitochondria (mituhKAHNdreeuh): d. e. f. ﬂ7.msscience.com ribosome ribosome lysosome mitochondrion tissues thatworktogether w protein own and water release energybybreakingdownfoodintocarbondioxide or othercells energy andothersmakesubstancesneededbythecell a groupofsimilarcellsthatworktogethertodoonejob a structuremadeupoftwoormoredifferenttypes a smallstructurewherecellmakesits a structurewithineukaryoticcell;someprocess or Both to accessyourtextbook,interactive to show where the directs allcellactivities Organism organelles that

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. two to four movable objective lenses. microscopes Compound light have or two tubelike structures. Theeyepiece lensesare placed inone lenses andobjective lenses. lenses—eyepiece compound microscope light has two setsof The It lens. islike amagnifying microscope hasjustonelens. 270 The microscope’s lenshadapower of upto size. things 270timestheirnormal imagesof magnify It could simple microscope atiny beadforalens. with glass thecell soyou canseeitsparts. enlarges theappearance of has oneormore toward lensesthatdirects light your eye and microscope A small thatyou needamicroscope to seethem. Most cells are so youthings can’t seeare onlyonecell insize. the Most of can’t seeisgreater thanthenumber you cansee. What are modern microscopeslike?What aremodern microscopeslike?What were early Magnifying Cells you what describe saw. or amicroscope? Onthelinesbelow, Have you ever lens looked atanything usingamagnifying always orclear. sharp but thatimagewasnot microscopes madeanimage larger, section oa hr r ipeadcmon irsoe.Asimple Today there are simpleandcompound microscopes. Antonie vanLeeuwenhoek madea In themid-1600s, inyour things living environment thatyou The number of chapter Read toLearn Before You Read 11 3 and enterprise; Benchmarks—SC.H.1.3.3: Also covers: people, indifferentcultures,attimes… ● 2 SC.H.1.3.1; SC.H.1.3.4;SC.H.1.3.5;SC.H.1.3.6 SC.H.3.3.5: Cells Viewing Cells The studentunderstandsthatcontributionsto…science,mathematics,andtechnologyhavebeenmadebydifferentkindsof The studentknowsthatsciencedisciplinesdifferfromoneanother…buttheyshareacommonpurpose,philosophy, Early . have readthissection. about microscopesafteryou column withfactsyoulearned microscopes. Fillinthethird wanttoknowabout you second column,writewhat about microscopes.Inthe column, writewhatyouknow into threecolumns.Intheﬁrst ● K-W-L lcrnmicroscopes. electron light microscopesand below. Comparecompound three-tab Foldable,asshown B What You’llLearn ■ ■ Compare Study Coach to thecelltheory the discoveriesthatled microscopes the differencesamong

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Electron 181 Picture This ● facts aboutthecelltheory Foldable, asshownbelow,tolist C 1. 182 Describe cell theoryinthetable. Virchow’s contributionto Identify Cells

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What? Highlight Rudolf Make afour-tab . larger than its actual size.larger thanitsactual 430 described inthetablebelow.described n hs fotherscientistsare calledthe and thoseof Virchow’s ideasaboutcells from a cell thatalready existed. He cell came suggested thatevery to newcells. divide form cells. are things living madeof scientists puttheirideastogether andconcluded thatall Thesetwo cells. concluded thatallanimalsare madeof He Theodor Schwann different observed animal cells. cells. He concluded thatallplantsare madeof study plants. which henamedcells. littleboxes, empty madeupof was He thecork looked thought like it under amicroscope. produced. orelectronically images must bephotographed Electron microscope upto times. onemillion magnify So electrons. direct beamsof microscope field inavacuumto usesamagnetic electron An electron microscope. microscopes an with canbeviewed Magnification What discoveries ledtothecelltheory? Cell Theory objects? magnify How doesanelectronmicroscope oe f10 a power of theeyepiece lenshas if For example, compound microscope. a objective lensesdetermine of thetotal magnification theeyepiece and Thepowers of is calledmagnification. then the total magnification is430 then thetotal magnification .Alognssaemd Anorganismcanhaveoneormanycells. Allorganismsaremade 1. .Alclscm rmcls Mostcells candivideto form two Allcellscome fromcells. 3. Evenincomplexorganismssuchas Thecellisthe basicunitof 2. eea er ae,Rdl Virchow hypothesized thatcells Rudolf Several years later, Matthias Schleiden usedamicroscope to In the1830s, cork Robert Hooke looked atathinslice of In 1665, thatareThings compound too to small beseenwith light raiaini raim.hmn,tecl stebscui flife. humans,thecellisbasic unitof organization inorganisms. Mostplantsandanimalshavemanycells. up ofoneormorecells. irsoecnmk niaeo anobject430times microscope canmake animageof The largerimageproduced by amicroscope n h betv eshsapwro 43 and theobjective lenshasapower of new cellsthatareexactlythe same. The CellTheory me electron microscopes can (10 c times 43 e l l the o r y , .A ). as ,

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. 2. 1. cell theory: Mini Glossary How didtheK-W-L helpyou chart aboutmicroscopes? organize theinformation theory. cell Complete thetablebelow to listthediscovery madeby each scientist thatledto the the cell theory. thescientistconnected of to thatpart Include thenameof thecell theory. of part Write asentence one describing Review theterm anditsdefinitionintheMini Glossary. After You Read organisms; andallcellscomefromother more cells;thecellisbasicunitoforganizationin atisShednTedrShanRudolfVirchow TheodorSchwann Matthias Schleiden states thatallorganismsaremadeupofoneor games, andprojectstohelpyou learnmoreaboutviewingcells. Visit fl7.msscience.com to accessyourtextbook,interactive Reading Essentials Section End of 183 multiply?”. question “Howdoviruses second sheet,answerthe “What areviruses?”.Onthe first sheet,answerthequestion paper, asshownbelow.Onthe quarter-sheets ofnotebook the quizzes. Together discusstheanswersto quizzes withanotherstudent. under eachheading.Exchange question aboutthemainidea ● Create aQuiz D section 184 ■ ■ ■ What You’llLearn chapter Identify Study Coach some usesofviruses people how vaccineshelp how aviruscopiesitself 11 3 Also covers: disciplines differfromoneanotherintopic,techniques,andoutcomes…; Benchmark—SC.G.1.3.1 AnnuallyAssessed: viruses? Cells What are ● 3 Make SC.H.1.3.1; SC.H.1.3.2;SC.H.1.3.5;SC.H.1.3.6;SC.H.3.3.5 Cells Write a Viruses multiply? How do viruses The studentknowsthatvirusesdependonotherlivingthings; have the help of a living cell aliving called a have thehelpof about viruses. scientistsonly hypothesized Before thattime, microscopes. wereThey discovered whenscientistsbeganusingelectron shapes. Viruses have of avariety lacks acell membrane. A viruses. are called somediseasescausedby particles nonliving How do viruses multiply? How doviruses What arecharacteristicsofviruses? What areviruses? helpprevent. diseasestheseshotswill of listthekinds Onthelinesbelow, office oratahealthclinic. Think aboutthevaccinations you have hadatyour doctor’s surrounded by aprotein coating. tcnb ihratv rltn,wihi niatv stage. which isaninactive It canbeeitheractive orlatent, quickly. canmultiply they they enter anorganism, if Then, canbestored foryears. someviruses of forms iu a aeacp fisl.Avrs oee,must however, Avirus, itself. canmake acopyA virus of Viruses are microscope. too alight smallto beseenwith It also doesn’tA virus have a nucleus orotherorganelles. and AIDS theflu, colds, chicken pox, measles, Cold sores, Once a virus enters a host cell, the virus canactintwo ways. thevirus entersOnce ahostcell, avirus Read toLearn Before You Read v ir SC.H.2.3.1: us is a strand of hereditary material hereditary of is astrand The studentrecognizesthatpatternsexistwithinandacrosssystems. SC.H.1.3.3: host c The studentknowsthatscience e l l . Crystallized

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. no harm. butitishidinganddoing isstillinyour body’svirus cells, The has become latent thevirus again. cold sore goesaway, When the isactivevirus anddestroying cells inyour lip. cold The sore thatthe isasign body hasbecome active. active. something insideoroutsidethebody canmake thevirus atany time, Then, canbeinactiveA virus formany years. thevirus’s DNA iscopied. As thehostcell reproduces, cell. it doesnotimmediately ordestroy make newviruses the Unlike anactive virus, thecell’s material. hereditary of part canbecome material itshereditary enters ahostcell, virus active works insideacell. virus Follow thesteps inthefigure below to seeoneway thatan Thisprocess destroys thehostcell. cell to make newviruses. What happens when a virus islatent? What happenswhenavirus isactive? What happenswhenavirus Host cell a specifichostcell. The virusattachesto the hostcell. material enters hereditary The virus‘s If you have a cold sore on your lip, a latent virus inyour latent a virus you have acold sore onyour lip, If When alatent orinactive. canbelatent, Some viruses itcausesthehost When enters acell avirus andisactive, Nucleus Virus material Viral hereditary Viral proteins hereditary materialandproteins. virus causesthecelltomakeviral The hereditarymaterialofthe destroyed. open andis host cellbursts released asthe New virusesare inside thehostcell. New virusesform Picture This 1. 2. forming insideahostcell. step thatshowsnewviruses the hostcell.Highlight hereditary materialentering step thatshowsthevirus’s Sequence Describe a hostcellreproduces. to alatent Reading Essentials virus’s DNA what happens Circle the 185 when Picture This 4. 3. 186 attached tothecell. the placeswherevirusis Define Identify Cells the term Circle eachof vaccine. rabies virus caninfecthumans andmany virus otheranimalhosts. rabies The cells. caninfectmany Afewviruses kindsof crops. thepotato infectsonlypotato leafroll virus For example, cells. kindsof caninfectonlycertain Someviruses prokaryotes. iess nldn hce o,mals andmumps. measles, includingchicken pox, diseases, Vaccines have beenmadeto prevent many disease anymore. It ismadefrom thatcannotcause weakened materials virus 100viruses. cell releases anaverage of Each virus-infected The entire cycle takes about20minutes. material. attaches itshereditary to andinjects abacterium differfrom They otherkindsof jihz). Abacteriophage fay intheway enter thatthey bacteria. viruses uh ee TIHR (bak hostcell. attackonlyonekindof most viruses Thisiswhy asshown below. the hostcell must fittogether, andtheplace where virus itattaches The on the hostcell. firstattaches to thesurface of thevirus anorganism, infects When avirus a hostcell or by by beinginhaled. thewind to canbecarried avirus For example, can reach a cell host. How do viruses affectorganisms? How doviruses Fighting Viruses Fighting What arebacteriophages? reachahostcell? How doesavirus iue takaias lns ug,poit,andall protists, fungi, plants, Viruses attackanimals, acn sakn fmedicineusedto prevent adisease. A vaccine isakindof Viruses are thatinfectbacteria called bacteriophages There are several ways it cannotmoveA virus by itself. Virus Cell membrane

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. help people with geneticdisorders andfindacurehelp peoplewith forcancer. scientistshopeto Using genetherapy, material. hereditary entersin thealtered thecells andreplaces viruses theflawed material hereditary Thenormal flawed material. hereditary then are usedto thosecellsviruses infect thatcontain Thesealtered isplaced material into viruses. hereditary Normal foracell’smaterial flawed material. hereditary substitutes hereditary normal genetherapy, called One use, spread diseasecanbekept undercontrol. that such asmosquitoes, Animals, from healthy people. People whohave diseasescanbekept away viral improved. conditions can be Sanitary get vaccinated diseases. against sideeffects. harmful have becausethey are notusedwidely thesedrugs of Some are helpfulagainstviruses. Afewdrugs avirus. fight protective materials. Interferons causethenoninfected cells to make host. cellsby andmove virus-infected to noninfected cells inthe Interferons are proteins thatare madequickly interferons. protected themfrom smallpox. Thecowpox vaccine cowpox vaccine into healthy people. He injected the peoplewhohadcowpox. the sores of He madeavaccine from got cowpox didnotget smallpox. Jenner noticed thatpeoplewho vaccine wasforsmallpox. Research withViruses How canviraldiseasesbeprevented? How areviraldiseasestreated? How was vaccinedeveloped? thefirst Scientists are discovering helpfulusesforsomeviruses. People can There are many ways to diseases. prevent viral canbegiven drugs Antiviral to aninfected patientto help One way infectionsisby your making viral body canfight The Edward Jenner developed thefirstvaccine in1796. 5. 6. the firstvaccine? Identify Describe diseases canbeprevented. Reading Essentials Who developed one wayviral 187 3. 2. 1. host cell: Mini Glossary 188 Complete below to thediagram identifytwo canactinsidehostcells. ways viruses your answer Thenwrite to thatquestiononthelinesfollow. the space below. Write thequestionin intheRead thequestion headings to section. Learn Choose oneof andahostcell. therelationship betweendescribes avirus Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section Write yourquestionhere. End of Cells a livingcellthatvirusenters Viruses enterhostcellsandbecome or games, andprojectstohelpyou learnmoreaboutviruses. Visit virus: fl7.msscience.com coating thatcaninfectandmultiplyinahostcell a strandofhereditarymaterialsurroundedbyprotein to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chapter Classifying Plants 123 section ●1 An Overview of Plants Benchmarks—SC.F.2.3.4: The student knows that the fossil record provides evidence that changes in the kinds of plants and animals in the environment have been occurring over time; SC.G.1.3.2: The student knows…biological adaptations…enhance reproductive success in a particular environment; SC.G.1.3.3: The student knows…the classiﬁcation of living things is based on a given set of criteria and is a tool for understanding biodiversity and interrelationships. Before You Read What You’ll Learn ■ the characteristics What are your favorite plants? Why are they your favorites? common to all plants ■ the adaptations that make it possible for plants to live on land ■ how vascular and nonvascular plants are similar and different

Read to Learn Study Coach Identify Answers Read What is a plant? each question heading aloud. When you have finished reading Plants include trees, flowers, vegetables, and fruits. More the section, read the question than 260,000 plant species have been discovered and heading again. Answer the identified. Scientists expect more species will be found, question based on what you mostly in tropical rain forests. Plants are important sources have just read. of food for humans. Most life on Earth would not be possible without plants. All plants are made of cells and need water to live. Many have roots that hold them in the ground or onto an object such as a rock. Plants come in many sizes and live in almost every environment on Earth, including cold, icy regions and hot, dry deserts. What are the parts of a plant cell? Every plant cell has a cell wall, a cell membrane, a nucleus, and other cell structures. A cell wall surrounds every plant cell. The cell wall gives the plant structure and provides protection. Animal cells do not have cell walls. Many plant cells have a green pigment, or coloring, called 1. Explain What surrounds chlorophyll (KLOR uh fihl). Chlorophyll traps light energy every plant cell?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright that is used to make food. Chlorophyll is found in cell structures called chloroplasts. The green parts of a plant usually have cells that contain many chloroplasts.

Reading Essentials 189 3. 2. 190 drought affectgreenalgae? Determine Conclude have incommon? plants andgreenalgae Classifying Plants What do How woulda adaptations thatallow themto conserve water. Landplants have die. thealgaewill up, thewater dries If and leave through thealgae’s cell andcell membranes walls. Thewater anddissolved enter nutrients surrounds them. thatarealgae neednutrients dissolved inthewater that To stay alive, make foodthrough theirown photosynthesis. became anenvironment inwhich landanimalscould live. Earth’s atmosphere thisincrease inoxygen, Because of more oxygen wasaddedto Earth’s atmosphere. asmore plants grew onland, years, Over millionsof oxygen. plants give off photosynthesis, During dioxidecarbon forphotosynthesis. and Plantsneedsunlight available onlandthaninwater. dioxideadvantage andcarbon isthatmore sunlight are flowering plants. of beginning Scientistsdonotknow the exact 120 millionyears ago. Plants thathave flowers mostlikely didnotexist untilabout evolved from plantsthatlived about350millionyears ago. theseearlyplantsevolved into theplantsthatlive today. of Scientistshypothesize thatsome about 420millionyears old. Theoldestplantfossilsare plants. of some fossilevidence But there is Plantsusuallydecay instead. become fossils. have come from thesameancestor. may they chlorophyll, of haveand green algae thesametype Because plants outphotosynthesis. organisms thatcancarry Green algaeare one-celled ormany-celled in thesea. Theirancestors may have beengreen algaethatlived areas. Central Vacuole Adaptations toLand Life onLand Origin andEvolutionofPlants h imnsta aesm oesrd le rpurple. or blue, thatmakethe pigments someflowers red, including substances alsoare stored vacuole, inthecentral Many other thecell. vacuole controls thewater content of Thecentral up by alargestructure calledthecentral vacuole. la iei ae ri eymitevrnet.They Algae live moistenvironments. inwater orinvery One Life onlandhassomeadvantages for plants. probably such aspinetrees, Plants thathave cones, Plants donothave thatcan bonesorotherhard parts The firstlandplantsprobably could onlyindamp survive oto thespace insideaplantcell istaken Most of

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. (VAS kyuh lur) andnonvascular plants. environmental conditions are right. grow They into the newplantswhen conditions. andotherharsh cold, dryness, cansurvive structures cu many landplantsare covered a with andflowers of leaves, stems, The have adaptationsthathelpthemconserve water. nomenclature (biNOHmeeul• NOH mun klay chur). He alsodeveloped away to nameplants calledbinomial Carolus Linnaeusdeveloped asystem to classifyplants. aSwedish scientistnamed In century, the eighteenth illinoiensis thescientificnameforapecantree is For example, not have these tubelike structures. Classification ofPlants How doplantsreproduceonland? fortheplant. alsohelpprovideThese structures support andfoodto plantcells. all nutrients, that deliver water, developed structures inmany plants Through adaptations, by water anddissolved thatcanmove nutrients into thecell. strong cell walls. for buildingbecauseof Wood from trees canbeused these strong cellwithout walls. could notgrow such asoaksandpines, Trees, even stronger. Thesesubstances helpmake thecell walls besides cellulose. andsupport. the plantstructure Thesefibersgive fibersinplantcellmolecules form walls. cellulose Longchains of sugar. plants canmake outof Celluloseisachemical compound that (SEL yuhlohs). andprotected? How arelandplantssupported The cell wallsthatsurround allplantcells contain onland. that helpsplantssurvive cuticleisastructure The water. layer thatslows thelossof usacst l h el ftheplant. substances to allthecells of andother nutrients, water, tubelike thatcarry structures lnscnb lsie notomjrgop,vascular Plants canbeclassifiedinto two majorgroups, These Land plantsreproduce by spores forming orseeds. Plantsthatlive onland Plants cannotlive water. without Scientists give each two-word plantspeciesitsown name. Life onlandmeansthateach plantcell isnotsurrounded someplantscontain othersubstances The cell walls of Land plantsalsohave to themselves. beableto support t ic le KE i u) h uil sawx,protective Thecuticleisawaxy, (KYEW tihkul). and thenameforawhite oakis N V o n ascular plants v ascular plants Quercus alba. c e Carya l l ulose have do ● sentence definitionoftheword. the tabs.Inside,writeacomplete List eachvocabularywordon book Foldable,asshownbelow. A 4. 5. Define Identify Recall groups ofplants. water. plant thatslowsthelossof Reading Essentials the twomajor Make afour-tab the partof 191 2. 1. cuticle: cellulose: Mini Glossary 192 One adaptationissuppliedforyou. fouradaptationsinplantsthatallow themto describe live onland. In theboxes below, explains thedifference between vascularandnonvascular plants. Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After YouAfter Read Section lns lnsmk toto sugar plants; plantsmakeitoutof End of a waxy,protectivelayeronthesurfaceofplant Classifying Plants a chemicalcompoundthatformsthewallsof Plant AdaptationsforLifeonLand games, andprojectstohelpyou learnmoreaboutplants. Visit vascular plants: nonvascular plants: n nutrients and developed structurestodistributewater fl7.msscience.com of theplant carry water,nutrients,andothersubstancestothecells other ways move waterandothersubstancesthroughtheplantin plants thathavetubelikestructuresto plants withouttubelikestructures; to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. plants do not have roots. Instead, they have they Instead, plants donothave roots. Nonvascular thatlooklikestructures stems andleaves. Nonvascular plantshave only about2cmto 5cmhigh. are tall, They notvery usually are onlyafewcells thick. Nonvascular plants plants thatgrow from seedhave. that theparts alsodo not have They allof spores. forming reproduce they by Instead, donotgrowthey from seeds. nonvascular plantsare calledhornworts andliverworts. Someother clumpsonmoistrocksgreen orstream banks. which you may have seenas includemosses, They notice. their cell andcell membranes walls. water through absorb They plants grow indampplaces. Most nonvascular anchor theplantswhere grow. they Rhizoids are threadlike structures thathelp zoydz). (RI nonvascular plants? What arecharacteristicsofseedless Seedless Nonvascular Plants keep alive afern indoors? What doyou thinkyou would needto doto house plant. seedlessplantthatisoften grown asa of Ferns are atype section ovsua lnsd o aeflwr rcns and Nonvascular plantsdonothave flowers orcones, Nonvascular plantsare smallandnotalways easyto chapter Read toLearn Before You Read 12 3 Benchmarks—SC.F.1.3.1 AnnuallyAssessed: Also covers: plants andanimalsintheenvironmenthavebeenoccurringovertime. reproduction, growth,maintenance,andregulation; ● 2 SC.D.1.3.4; SC.H.1.3.5 Classifying Plants Seedless Plants The studentunderstandsthatlivingthingsarecomposedofmajorsystemsfunctionin SC.F.2.3.4: The studentknowsthatthefossilrecordprovidesevidencechangesinkindsof r hiz o ids heading inthesection. with theinformationundereach the outline.Completeoutline section asthemainheadingsin Use themainheadingsin the informationinsection. make anoutlinetosummarize Summarize 1. What You’llLearn ■ ■ Study Coach help aplant? Identify vascular plants nonvascular and the importanceofsome seedless vascularplants nonvascular plantsand between seedless the differences Reading Essentials As youread, How dorhizoids 193 Mosses The largest group of nonvascular plants is the mosses. Mosses have green, leaflike growths on a stalk. Their ●B Organize On quarter rhizoids are made of many cells. Like all nonvascular plants, sheets of notebook paper, make notes about characteristics of mosses reproduce by forming spores. In many moss species, vascular and nonvascular plants. a stalk with caps grows from the plant when it is ready to reproduce. Spores are produced in the cap. Mosses often Vascular Nonvascular grow on tree trunks, rocks, or the ground. Most mosses live in damp places, but some can live in deserts. Liverworts Liverworts got their name because people who lived during the ninth century used them to treat diseases of the liver. Liverworts have flattened, leaflike bodies. They usually have one-celled rhizoids. Hornworts Hornworts have flattened, leaflike bodies like liverworts. Hornworts are usually less than 2.5 cm in diameter. Hornworts have one chloroplast in each of their cells. They get their name from the structures that produce spores, which look like tiny cattle horns. How are nonvascular plants important? Nonvascular plants need damp conditions to grow and reproduce. However, many species can withstand long, dry periods. Nonvascular plants can grow in thin soil and in soils where other plants cannot grow. The spores of these plants are carried by the wind. When a spore lands on the ground, it can grow into a new plant only if there is enough water and if other growing conditions are right. Mosses, such as those pictured below, often are the first plants to grow in a new or disturbed environment, such as Inc. w-Hill Companies, after a forest fire. Organisms that are the first to grow in new or disturbed areas are called pioneer species. As pioneer plant species die, they decay. The decayed matter builds up. The decaying material and slow breakdown of rocks build soil. After enough soil is made, other organisms can move into the area.

Aaron Haupt

194 Classifying Plants Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. places have becausethey beenover-collected by humans. Ground pinesare endangered insome cold and hotareas. Ground pinesgrow inboth that looklike tiny pinecones. the stems instructures Theirspores attheendof form leaves. Clubmosseshave needle-like related to than to ferns mosses. Clubmossesare more closely often are calledclubmosses. 5 mtallandgrow intropical areas. m to today Thetallestferns are 3 that grew astall as 25m. ferns Thetallestplantswere speciesof steamywith swamps. wascovered Earth much of that360million yearslearn ago, Scientistshave usedcluesfrom rock layers to existed longago. many more species today, are ferns foundonEarth species of thousandsof Although thefronds. on theundersideof Spores found instructures form intheﬁgureshown below. as Fern leaves are called fronds, and roots. leaves, have stems, 360millionto 286millionyears Earth ago. much of Theseplantscovered arefossils becausethey now extinct. Many speciesare onlyfrom known andhorsetails. mosses, water to andnutrients allplantcells. vascular tissuecarries grow largerandthicker thannonvascular plantsbecausethe Vascular plantscan andfoodthroughout theplant. minerals, What areclubmosses? What areferns? What arethetypesofseedlessvascularplants? Seedless Vascular Plants rudpnsadsiemse r ruso plantsthat Ground pinesandspike mossesare groups of Ferns seedlessvascularplants. Ferns are thelargestgroup of spike ground pines, Seedless vascularplantsincludeferns, water, tubelike cells thatcarry Vascular tissueismadeupof Root Fronds Rhizome Stem Picture This 4. 3. for plants? vascular tissueanadvantage spores arefound. of thestructurewhere Explain Identify Reading Essentials How ishaving Circle thename 195 5. 6. 196 vascular plants? horsetails differfromother Identify Explain seedless plantsareused. Classifying Plants two ways How do sometimes are woven into bask plantsfor sold aslandscape that over timepeatthatremains become inabogwill coal. Scientistshypothesize in places such asIreland andRussia. Peat isminedto useasalow-cost fuel substance peat. called thedecaying plantsare pressed into a Over time, process. that live are inbogs seedlessplantslike mossesandferns. Most plants landthatcontains decaying plants. area of watery into turned coal.this material years, Over millionsof pressed onthelayers down below. Top layers becameheavy and builtup. thisplantmaterial of many layers Over time, into water andmud before decaying. for polishingobjectsandscouring cooking utensils. horsetailswere used In thepast, substance foundinsand. agritty horsetailscontain silica, Thestems of some stems. Horsetail spores inconelike form atthetipsof structures Leaves grow outfrom thestem ateach joint. has joints. Thestem also vasculartissue. surrounded of by aring Thestem hasahollow center other vascularplants. Spike Mosses How areseedlessvascularplants used? ofSeedlessPlants Importance vascular plants? differentfromother How arehorsetails curl upagainwhenever conditions make itnecessary. Theplantcan its green leaves makingfoodagain. andbegins theresurrection plantunfolds When water becomes available, theplantcurlsupandlooksdead. water, there isnotenough When lives areas. indesert theresurrection plant, species, and fevers. burns, have ferns been usedto treat beestings, For example, years. plants have beenused asmedicinesforhundreds of Some seedless Peat isusedto garden enrich soil. into ﬂour. canbeeaten. someferns of aypol epfrsa ospat.Ferns alsoare Many people keep ashouseplants. ferns soilslows thedecaying thewatery When bogplantsdie, A bogisa thesameprocess ishappeninginbogs. Today, sank they when ancientseedlessplantsdied, Long ago, Horsetails have astem thatisdifferent structure from h re tm foekn fhorsetail canbeground onekindof stems of The dried pk ossrsml rudpns One Spike mossesresemble ground pines. hd udo ra.Ferns shady outdoor areas. ets. The rhiz The ets. omes andfronds

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. After You Read Mini Glossary pioneer species: organisms that are the ﬁrst to grow in rhizoid: threadlike structures that anchor nonvascular plants new or disturbed areas

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence to explain the importance of pioneer species to the environment.

2. Complete the Venn diagram below to compare nonvascular and vascular seedless plants. Include phrases that describe how the plants get nutrients and how they reproduce. Nonvascular Seedless Plants Vascular Seedless Plants

Both Nonvascular and Vascular Seedless Plants

3. How did summarizing the information in this section help you learn about nonvascular and vascular seedless plants? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Visit ﬂ7.msscience.com to access your textbook, interactive End of games, and projects to help you learn more about seedless plants. Section

Reading Essentials 197 stems, androots. the importanceofplantleaves, Foldable towritenotesabout ● idea. detail thatsupportsthemain paragraph. Thenunderlineone Highlight themainideaineach Identify Main Ideas C section 198 ■ ■ ■ ■ What You’llLearn chapter Classify Study Coach dicots aredifferent how monocotsand angiosperms gymnosperms and the characteristicsof leaves function how roots,stems,and seed plants the characteristicsof 12 3 SC.H.3.3.4; SC.H.3.3.5;SC.H.3.3.6 Also covers: Benchmarks—SC.F.1.3.1 AnnuallyAssessed: Classifying Plants

Leaves Stems Roots Make athree-tab ● 3 SC.F.1.3.2; SC.F.1.3.3;SC.F.1.3.4;SC.F.1.3.5;SC.F.1.3.6;SC.F.2.3.3;SC.G.1.3.3;SC.H.1.3.2;SC.H.1.3.4;SC.H.1.3.5;SC.H.1. Classifying Plants Seed Plants called Most leaves have intheepidermis openings small cuticle. someleaves iscovered awaxy with of Theepidermis leaf. the coversthe epidermis andprotects thetop andbottom of andcolors. sizes, Leaves come inmany shapes, food-makingprocess The iscalledphotosynthesis. made. and vasculartissue. leaves, stems, roots, Most seedplantshave fourmainparts: (ANjeeuhspurmz). andangiosperms nuh spurmz) (JIHM gymnosperms Scientists classifyseedplantsinto two groups: sothatitcangrow fortheembryo into aplant. energy stored The foodprovides andstoredplant embryo food. and exit theleaf. andoxygen to enter water, stomata dioxide, allow carbon open andclosethestoma. What arethecelllayers ofaleaf? Why areleaves important? Characteristics ofSeedPlants comefruits from? plantdothese What are your favorite fruits? of What type The studentunderstandsthatlivingthingsarecomposedofmajorsystems… efhssvrllyr fcls hnlyro cells called Athinlayer of cells. hasseveral layers of A leaf seedplantsare theorganswhere foodis The leaves of Aseedcontains a Seed plantsreproduce by seeds. forming Read toLearn Before You Read st o mata (STOH muh tuh)(singular, G uar d c e l ls located around each stoma 3.6; SC.H.2.3.1; stoma .The ).

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. tm rnhs andleaves. branches, stem, theplantthatare above ground—the of the parts support Roots and prevent themfrom orwashedaway. beingblown Roots alsoanchor plants through thestems to theleaves. substances from the soilmove into theroots andup Water anddissolved Roots contain vasculartissue. plant. atree isastem. of Thetrunk shrubs. trees and like thoseof Woody stems are hard andrigid, apetunia. like thoseof Herbaceous stems are softandgreen, plants alsostore foodandwater. some stems The of through vasculartissuesinthestem. Materials move between theleaves androots the plant. andreproductive of structures leaves, thebranches, support l h at ftela canbeseenintheﬁgure below. theleaf of All theparts vasculartissueandare layer. located inthespongy made of are aleaf Theveins of cells separated byarranged airspaces. loosely layer Thespongy ismadeof the lower epidermis. the palisadecells. theirfoodin Plantsmake mostof that contain chloroplasts. narrow cells Thislayer haslong, below theupperepidermis. Why areplantroots important? ofaplant’sWhat isthepurpose stem? epidermis Lower layer Spongy layer Palisade epidermis Upper Palisade Layer h otsse fms lnsi h ags ato the of mostplantsisthelargestpart The root system of Plant stems canbewoody (hur orherbaceous BAY shus). They Plant stems are foundabove usually theground. The spongy layerThe spongy isfoundbetween thepalisadelayer and Phloem Xylem h aiaelyro efislocated just aleaf The palisadelayer of Vein Guard cells Stoma Cuticle Picture This SC.F.1.3.1 ✔ FC A 1. T

F F

the leaf. oxygen toenterandexit carbon dioxide,water,and part oftheleafthatallows underline thenameof protects theleaf.Finally, red theplantlayerthat the chloroplasts.Colorin the plantlayerthatcontains Identify

O O

2. roots doforaplant. C C

U U S S Identify Benchmark Check Annually Assessed Reading Essentials Color inblue two things 199 Functions of Roots Roots can store food and water. They can take in oxygen that the plant needs for the process of cellular respiration. For plants that grow in water, part or all of a plant’s roots may grow above ground. Water does not have as much oxygen as air. The roots take in more oxygen from the air. What are vascular tissues made of? The vascular system in a seed plant contains three kinds of tissue—xylem, phloem, and cambium. Xylem (ZI lum) tissue is made of hollow, tubelike cells that are stacked one on top of the other to form a structure called a vessel. Vessels move water and dissolved substances from the roots to the rest of the plant. Xylem’s thick cell walls also help support the plant. Phloem (FLOH em) tissue is made of tubelike cells that are stacked to form structures called tubes. Phloem tubes move food from where it is made to other parts of the plant where the food is used or stored. 3. Describe What does Some plants have a layer of cambium tissue between phloem tissue do? xylem and phloem. Cambium (KAM bee um) tissue produces most of the new xylem and phloem cells. Gymnosperms Gymnosperms are vascular plants that produce seeds that are not protected by a fruit. Gymnosperms do not have ﬂowers. The leaves of gymnosperms are usually shaped like

needles or scales. Many gymnosperms are called evergreens Inc. w-Hill Companies, because some green leaves always stay on their branches. The gymnosperms are divided into four divisions. These four divisions are conifers, cycads, ginkgoes, and gnetophytes (NE tuh ﬁtes). The conifers are the most familiar gymnosperm division. Pines, ﬁrs, spruces, redwoods, and junipers are conifers. Conifers produce two types of cones—male and female. Seeds develop on the 4. Compare What is the female cone but not on the male cone. difference between gymnosperms and Angiosperms angiosperms?

An angiosperm is a vascular plant that ﬂowers and a division of The McGra © Glencoe/McGraw-Hill, Copyright produces fruit with one or more seeds. Peaches, apples, and tulips are examples of angiosperms. Angiosperms are common in all parts of the world. More than half of all known plant species are angiosperms.

200 Classifying Plants Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. eenas Most are trees andshrubs perennials. perennials. lifecycles thattakewith longerthantwo years are called Angiosperms growth. thesecondseeds onlyduring year of Biennials produce flowers and biennials (biEHneeulz). Annuals must begrown from newseedseach year. that completes itslifecycle inoneyear anannual. iscalled Aplant long as100years to grow from seedsto maturity. Someplantstake as inlessthana month. seeds to maturity grow from angiosperms Some flowers and/orproduces seed. theseedandendswhenmature plant cycle with begins Theangiosperm’s life organism’s anddevelopment. growth and chairs are made from wood. Somedesks is madefrom wood pulp thatcomes from trees. Paper thefibersused inmakingclothes. many of source of are the Angiosperms foods you eatcome from seedplants. conifers. alsocomes andvarnish from paint, chemicals found insoap, Resin used to make used inbuildingcomes from conifers. thewood Most of the mostcommonly usedgymnosperm. stores foodforthenewplant. into two groups—monocots anddicots. are divided Angiosperms like astrawberry. on thesurface, have Somefruits seeds like anapple. havefruits seedsinside, Most aflower grow into afruit. of parts Some and colors. Importance ofSeed Plants Importance What isthelifecycleofanangiosperm? How domonocotsanddicotsdiffer? like?What aretheflowers ofangiosperms ios otsaetes uha asadmpe,are dicots. such asoaksandmaples, Most shadetrees, dicots. come andoranges from peas, Familiar foodssuch aspeanuts, Bananasandpineapplesalsoare monocots. and wheat. thathaveangiosperms two insidetheirseeds. cotyledons that have insidetheirseeds. onecotyledon Plants thatcomplete theirlifecycles intwo years are called nisem r ieyue yhmn.Mn fthe Many of usedby are humans. widely Angiosperms Conifers are areGymnosperms usedformany purposes. All organismshave a aseedthat of (kahtulEEdun)isthepart A cotyledon sizes, have angiosperms different shapes, The flowers of ayfoscm rmmnct,icuigcr,rice, includingcorn, Many foodscome from monocots, lif e cy c M le o —all theevents inan no c ots are angiosperms Dic ots are ● in whichhumansuseeach. two-tab Foldable.Includeways monocots anddicotsina listing thecharacteristicsof D 5. Compare ways peopleuseconifers? Explain ooosDicots Monocots Reading Essentials What aresome Make notes 201 After You Read Mini Glossary angiosperm: vascular plant that flowers and produces one monocot: angiosperm that has one cotyledon inside its seeds or more seeds inside a fruit phloem: plant tissue made up of tubelike cells that are cambium: plant tissue that produces most of the new xylem stacked to form tubes; tubes move food from where it is and phloem cells made to parts of the plant where it is used dicot: angiosperm that has two cotyledons inside its seeds stomata: small openings in the epidermis of the leaf guard cells: cells that surround a stoma and open and close it xylem: plant tissue made up of hollow, tubelike cells that are gymnosperm: vascular plant that produces seeds that are stacked one on top of the other to form vessels; vessels not protected by fruit transport water and dissolved substances from the roots life cycle: all the events in an organism’s growth and to all other parts of the plant development

1. Review the terms and their deﬁnitions in the Mini Glossary. Write two sentences that explain what xylem and phloem do.

2. Complete the chart below to list the four main parts of seed plants and describe what they do.

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about seed plants.

202 Classifying Plants chapter Plant Processes 133 section ●1 Photosynthesis and Cellular Respiration Benchmarks—SC.B.1.3.3 Annually Assessed: The student knows the various forms in which energy comes to Earth from the Sun; SC.F.1.3.6: The student nows that the cells with similar functions have similar structures, whereas those with different structures have different functions. Also covers: SC.B.1.3.2; SC.F.1.3.5; SC.H.1.3.5; SC.H.1.3.6; SC.H.1.3.7; SC.H.2.3.1

Before You Read What You’ll Learn ■ how plants take in and Name the parts of a plant that you have seen recently. For give off gases one of the parts, describe its function. ■ the differences and similarities between photosynthesis and respiration ■ why photosynthesis and respiration are important

Read to Learn Study Coach Summarize Main Ideas Taking in Raw Materials As you read the section, write Plants can make their own food using water, carbon down the main ideas. Take notes on the facts that support the dioxide, and inorganic chemicals from the soil. Plants also main ideas. Then use your notes produce waste products. to summarize the main ideas of Which plant structures move water into this section. the plant? The ﬁgure below shows the plant structures that take in raw materials. Most of the water used by plants is taken in through the roots and moves through the plant to where it is used.

Picture This 1. Identify Circle the

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright names of the raw materials that a plant takes in.

Reading Essentials 203 What is the function of a leaf? Gas is exchanged in the leaves. Most of the water that enters roots of a plant exits the plant through its leaves. Carbon dioxide, oxygen, and water vapor enter and exit a plant through openings in its leaves. What is the structure of a leaf? A leaf is made up of many different layers. The outer layer of the leaf is called the epidermis. The epidermis is nearly transparent and allows light, which is used during food production, to reach the cells inside the leaf. The epidermis has many small openings called stomata (stoh MAH tuh) (singular, stoma). Raw materials such as carbon dioxide, water vapor, and waste gases enter and exit the leaf through the stomata. Many plants have stomata on their stems. Guard cells surround each stoma to control how much water enters and exits the plant. Stomata close when a plant is losing too much water. As you can see in the ﬁgure below, the inside of a leaf is made up of a spongy layer and a palisade layer. Carbon dioxide and water vapor ﬁll the spaces of the spongy layer. Most of the plant’s food is made in the palisade layer.

Picture This Upper Cuticle 2. Identify Circle the layer epidermis of the leaf where most of Palisade layer the plant’s food is made. w-Hill Companies, Inc. w-Hill Companies, Spongy layer Lower epidermis

Guard cells

Why are chloroplasts important? Some cells of a leaf contain small green structures called chloroplasts. Chloroplasts are green because they contain a

green pigment, or coloring, called chlorophyll (KLOR uh ﬁhl). a division of The McGra © Glencoe/McGraw-Hill, Copyright Chlorophyll is important to plants because the light energy 3. Describe What happens that plants absorb is used during food production. in the chloroplasts? Photosynthesis (foh toh SIHN thuh suhs), a food-making process, happens in the chloroplasts.

204 Plant Processes The Food-Making Process Photosynthesis is the process during which a plant’s ●A Describe Use two chlorophyll traps light energy and uses it to produce sugar. In quarter-sheets of notebook plants, photosynthesis occurs only in cells with chloroplasts. paper, as shown below, to take For example, photosynthesis occurs only in a carrot plant’s notes about photosynthesis. green leaves. The carrot’s root cells do not have chlorophyll, Light-dependent Light-independent so they cannot perform photosynthesis. But excess sugar reactions reactions produced in the leaves is stored in the root. The orange carrot you eat is the root of the carrot plant. When you eat a carrot, you beneﬁt from the energy stored as sugar in the plant’s root. Plants need light, carbon dioxide, and water for photosynthesis. The chemical equation for photosynthesis is shown below. chlorophyll → 6CO2 6H2O light energy C6H12O6 6O2 carbon water glucose oxygen dioxide What are light-dependent reactions? Some chemical reactions that occur during photosynthesis need light. These are called light-dependent reactions. During light-dependent reactions, chlorophyll and other pigments trap light energy that will be changed and stored in sugar molecules. Light energy causes water molecules in chloroplasts to split into oxygen and hydrogen. The oxygen exits the plant through the stomata. The hydrogen produced when water is split is used in reactions that do not need light. w-Hill Companies, Inc. w-Hill Companies, What are light-independent reactions? Other chemical reactions that occur during photosynthesis do not need light. These are called light-independent reactions. The light energy trapped during the light-dependent reactions is used to combine carbon dioxide and hydrogen. This process creates sugars, such as glucose. The chemical bonds that hold glucose and other sugars together are stored energy. What happens to the oxygen and glucose that are made during photosynthesis? 4. List two foods other than Glucose is the main form of food for plant cells. A plant carrots and potatoes that

Copyright © Glencoe/McGraw-Hill, a division of The McGra © Glencoe/McGraw-Hill, Copyright usually produces more glucose than it can use and stores it as are stored products of other sugars and starches. When you eat carrots or potatoes, photosynthesis. you are eating the stored product of photosynthesis. Oxygen is produced during photosynthesis. Most of the oxygen is released as waste through the stomata.

Reading Essentials 205 How does a plant use glucose? Glucose also is important to a plant’s structure. Plants grow larger by taking in carbon dioxide gas and changing it to glucose. Cellulose, an important part of plant cell walls, is made from glucose. Leaves, stems, and roots are made of cellulose and other materials produced using glucose. Why is photosynthesis important? Photosynthesis produces food. Photosynthesis uses carbon 5. Determine What does dioxide and releases oxygen. This removes carbon dioxide photosynthesis add to from the atmosphere and adds oxygen to it. Most organisms Earth’s atmosphere? need oxygen to live. About 90 percent of the oxygen in the atmosphere today is a result of photosynthesis. The Breakdown of Food Cellular respiration is the process of breaking down food and releasing energy that occurs inside cells. It occurs in many organisms. In many-celled organisms it usually occurs in the mitochondria. The overall chemical equation for cellular respiration is shown below. → C6H12O6 6O2 6CO2 6H2O energy glucose oxygen carbon water dioxide How does cellular respiration occur? Before cellular respiration begins, glucose molecules in the Picture This cytoplasm are broken down into two smaller molecules. These 6. Identify Circle the part molecules move into a mitochondrion. Oxygen breaks down of the cell where cellular the molecules into water and carbon dioxide and to release respiration occurs. Highlight the waste energy. The ﬁgure below shows cellular respiration in a products of respiration. plant cell.

Mitochondrion

C6H12O6 Small Oxygen is used in the molecules mitochondrion to break down these two molecules.

H2O In the cytoplasm, each glucose Water and carbon dioxide molecule is broken down into are waste products of two smaller molecules. cellular respiration.

206 Plant Processes Why is cellular respiration important? Food contains energy. But it is not in a form that can be used by cells. Cellular respiration changes food energy into a form that cells can use. This energy drives the life processes of almost all organisms on Earth. Plants cells use energy produced by cellular respiration to transport sugars, to open and close stomata, and to produce chlorophyll. When seeds sprout, energy released from stored food is used. The ﬁgure below shows some uses of energy in plants.

PlantPlant sstructuretructure Picture This andand ffunctionunction 7. List two uses of the energy produced by respiration ProductionProduction in plants. ofof chlorophyllchlorophyll

SproutingSprouting ofof sseedseeds

The waste product carbon dioxide also is important. Cellular respiration returns carbon dioxide to the atmosphere, where plants and some other organisms use it for photosynthesis. Comparison of Photosynthesis and Cellular Respiration Cellular respiration is almost the reverse of photosynthesis. Photosynthesis combines carbon dioxide and water by using light energy. This produces glucose (food) and oxygen. Cellular respiration combines oxygen and food to release the energy in the chemical bonds of the food. This produces energy, carbon dioxide, and water. Look at the table below to compare the differences between photosynthesis and cellular respiration.

Comparing Photosynthesis and Cellular Respiration Picture This Photosynthesis Cellular Respiration 8. Compare and Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Energy stored released contrast Highlight water and carbon dioxide for each Raw materials water and carbon dioxide glucose and oxygen process in one color and End products glucose and oxygen water and carbon dioxide glucose and oxygen in Where cells with chlorophyll cells with mitochondria another color.

Reading Essentials 207 After You Read Mini Glossary cellular respiration: a series of chemical reactions that photosynthesis (foh toh SIHN thuh suhs): the process breaks down food molecules and releases energy during which a plant’s chlorophyll traps light energy and chlorophyll (KLOR uh ﬁhl): a green pigment found in sugars are produced chloroplasts stomata (stoh MAH tah): small openings in the leaf epidermis, which act as doorways for raw materials to enter and exit the leaf

1. Review the terms and their deﬁnitions in the Mini Glossary. Write one or two sentences that explain the difference between photosynthesis and cellular respiration.

2. Choose one of the question headings in the Read to Learn section. Write the question in the space below. Then write your answer to that question on the lines that follow.

Write your question here.

3. How did your notes help you summarize what you read in this section? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about photosynthesis and respiration. 208 Plant Processes chapter Plant Processes 133 section ●2 Plant Responses Benchmarks—SC.F.1.3.7 Annually Assessed: The student knows that behavior is a response to the environment and inﬂuences growth, development, maintenance, and reproduction; SC.H.2.3.1: The student ecognizes that patterns exist within and across systems. Also covers: SC.H.1.3.5 Annually Assessed; SC.H.1.3.7 Annually Assessed

Before You Read What You’ll Learn ■ the relationship Have you ever been suddenly surprised? On the lines below, between a stimulus and describe what surprised you and how your body responded a tropism in plants to the surprise. ■ about long-day and short-day plants ■ how plant hormones and responses are related

Read to Learn

What are plant responses? Study Coach A stimulus is anything in the environment that causes a Create a Quiz Write a quiz response in an organism. A stimulus may come from outside question for each paragraph. Answer the question with (external) or inside (internal) the organism. An outside information from the paragraph. stimulus could be something that startles or surprises you. An inside stimulus is usually a chemical produced by the organism. Many of these chemicals are hormones. Hormones are substances made in one part of an organism for use somewhere else in the organism. Often plants respond to stimuli by moving toward or away from the stimulus. Plants respond to touch, light, and gravity. Most plant responses are slow and involve growth. Tropisms Some plant responses to external stimuli are called ●B Compare Make a tropisms (TROH pih zumz). A tropism can be seen as two-tab Foldable, as shown movement caused by a change in growth. It can be positive below, to compare inside and outside stimuli. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright or negative. A positive tropism would be growth toward a stimulus. A negative tropism would be growth away from a stimulus. You may have seen plants responding to touch, Inside Outside light, and gravity. Plants also can respond to electricity, Stimuli Stimuli temperature, and darkness.

Reading Essentials 209 Touch If a pea plant touches a solid object, it responds by growing faster on one side of its stem than on the other ●C Explain Make a two-tab side. As a result, the stem bends and twists around any concept map Foldable, as shown below, to describe and list object it touches. positive and negative tropisms. Light When a plant responds to light, the cells on the side of the plant opposite the light grow longer than the cells facing the light. Because of this, the plant bends toward the light. The leaves move and can absorb more light. This positive response to light is called positive phototropism. Gravity Plants respond to gravity. The downward growth of plant roots is a positive response to gravity. A stem growing upward is a negative response to gravity. Plant Hormones Plants have hormones that control the changes in growth that result from tropisms and affect other plant growth. These hormones include ethylene, auxin, gibberellin, cytokinin, and abscisic acid. How does ethylene affect plants? Many plants produce the hormone ethylene (EH thuh leen) gas and release it into the air around them. This hormone helps fruits ripen. Ethylene also causes a layer of cells to form between a leaf and the stem. The cell layer causes the leaf to fall from the stem. How does auxin affect plants? The plant hormone auxin (AWK sun) causes a positive Inc. w-Hill Companies, response to light in stems and leaves. The ﬁgure below shows the effect of auxin. When light shines on a plant from one side, the auxin moves to the shaded side of the stem where it causes a change in growth. Auxin causes plants to grow toward light.

Picture This Light 1. Describe Use the ﬁgure Cells on to describe to a partner Lack of shaded side how auxin affects a plant’s auxin on grow longer. response to light. lighted side a division of The McGra © Glencoe/McGraw-Hill, Copyright Auxin moves to shaded side

210 Plant Processes How do gibberellins and cytokinins affect plants? Two other groups of plant hormones also affect a plant’s growth. Gibberellins (jih buh REH lunz) can be mixed with water and sprayed on plants and seeds. This stimulates plant stems to grow and seeds to germinate. Cytokinins (si tuh KI nunz) promote growth by causing faster cell division. Cytokinins can keep stored vegetables fresh longer.

FO How does abscisic acid affect plants? T C A U C Annually Assessed

S Abscisic (ab SIH zihk) acid is a plant hormone that keeps F Benchmark Check seeds from sprouting and buds from developing during the SC.F.1.3.7 winter. This hormone also causes stomata to close in response to water loss on hot summer days. ✔ 2. Explain How does abscisic acid affect plants? Photoperiods A plant’s response to the number of hours of daylight and darkness it receives daily is called photoperiodism (foh toh PIHR ee uh dih zum). Because Earth is tilted, the hours of daylight and darkness change with the seasons. These changes in the number of hours of daylight and darkness affect plant growth. How does darkness affect flowers? Many plants must have a certain number of hours of darkness to flower. Plants that need less than 10 to 12 hours of darkness to flower are called long-day plants. These plants include spinach, lettuce, and beets. Plants that need 12 hours or more of darkness to flower are called short-day plants. These plants include poinsettias, strawberries, and ragweed. If a short-day plant receives less darkness than it needs to flower, it will produce larger leaves instead of flowers. 3. Infer Why could you What are day-neutral plants? produce long-day flowering plants in a greenhouse Plants that do not need a set amount of darkness to during winter months? flower are called day-neutral plants. They can flower within a range of hours of darkness. These plants include dandelions and roses. Knowing the photoperiods of plants helps farmers and gardeners know which plants will grow best in the area where they live. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 211 After You Read Mini Glossary auxin (AWK sun): a plant hormone that causes plant stems photoperiodism (foh toh PIHR ee uh dih zum): a plant’s and leaves to exhibit positive response to light response to the number of hours of daylight and darkness day-neutral plant: a plant that does not have a specific it receives daily photoperiod to flower short-day plant: a plant that needs 12 hours or more of long-day plant: a plant that needs less than 10 to 12 hours darkness to flower of darkness to flower tropism (TROH pih zum): a response of a plant to an external stimulus

1. Review the terms and their deﬁnitions in the Mini Glossary. Write one or two sentences to explain the differences among the long-day, short-day, and day-neutral plants.

2. Complete the cause-and-effect chart below to show how plant hormones affect plant growth. Cause Effect

Ethylene

Auxin

Gibberellin

End of Visit fl7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about plant responses. 212 Plant Processes Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. avs itissymmetrical. halves, a way thatallows theobjectto into bedivided similar in are arranged theparts If anobjectare arranged. of parts (SIHmuh tree). their symmetry have five common characteristics. however, Allanimals, come inmany different shapesandsizes. Animals you would getmany different answers. common, What issymmetry? Animal Characteristics onethingthattheseanimalshavewrite incommon. Then five animalsonthelinesbelow. List thenamesof section syusuydfeetgop faias you lookat will animals, As you study different groups of 5. 4. 3. 2. 1. you asked ten peoplewhatallanimalshave in If chapter Read toLearn Before You Read 14 Most animals canmove from place to place. broken into down substances cells can use. are Largefoodparticles Animals digesttheirfood. Animals cannotmake food. theirown (yeweukaryotic ker ee AH tihk)cell. organelles surrounded by iscalleda membranes Acell thatcontains anucleus and a membrane. are theorganelles surrounded by nucleus andmany of The Most animalcells have anucleus andorganelles. cells. different kindsof of All animalsare many-celled organismsthatare made 3 Also covers: Benchmarks—SC.H.2.3.1: ● SC.F.1.3.4; SC.F.2.3.3;SC.G.1.3.2;SC.G.1.3.3 1 Classifying Animals What isananimal? The studentrecognizesthatpatternsexistwithinandacrosssystems. S y mme t r y refers to theway the section. questions andanswerstostudy the paragraph.Use question withinformationfrom each paragraph.Answerthe the section,writeaquestionfor Quiz Yourself 1. ■ ■ What You’llLearn Study Coach Analyze move fromplacetoplace. reason animalsneedto and invertebrates between vertebrates the differences animals the characteristicsof Reading Essentials Name one As youread 213 What kind of symmetry do most animals have? Most animals have either radial symmetry or bilateral symmetry. An animal with body parts arranged in a circle around a central point has radial symmetry. As you can see in the figure below, a sea anemone has radial symmetry. An animal with radial symmetry can find food and gather information from all directions. Other animals that have radial symmetry are jellyfish and sea urchins. 2. Explain What two forms An animal with bilateral symmetry has parts that are of symmetry do most nearly mirror images of each other. You can draw a line animals have? down the center of its body to divide it into two similar parts. The figure below shows that a lobster has bilateral symmetry. A human also has bilateral symmetry. What is an asymmetrical animal like? An animal with an uneven shape is called asymmetrical (AY suh meh trih kul). Its body cannot be divided into halves that are similar. Look at the sponge in the figure below. Notice that you cannot draw a line down the center of its body to divide it into two halves that are similar. As you learn more about invertebrates, think about their body symmetry. Notice how body symmetry affects the way they gather food and do other things. Most animals have radial or bilateral symmetry. Only a few animals are asymmetrical.

Picture This 3. Classify Draw a simple human ﬁgure beside the Sea anemones animal with the type of have radial symmetry that humans symmetry. have.

Many sponges are asymmetrical.

214 Classifying Animals Animal Classification Animals have many characteristics in common. But when you think about the variety of animals you can name, you know that there are many different kinds of animals. Some animals have legs, others have wings. Some live on land, others live in water. Scientists use a classification system to place all animals into related groups. Applying Math Scientists separate animals into two groups—vertebrates (VUR tuh bruts) and invertebrates (ihn VUR tuh bruts). 4. Create a Circle Graph In the circle below, draw a These two groups are shown in the figure below. circle graph showing the Vertebrates are animals that have a backbone. Invertebrates percent of invertebrates and are animals that do not have a backbone. About 97 percent the percent of vertebrates. of all animals are invertebrates.

Animal Kingdom

Invertebrates Vertebrates

Scientists further classify the invertebrates into smaller groups, as shown in the ﬁgure below. The animals in each group share similar characteristics. These characteristics show that the animals within the group may have had a common ancestor.

Invertebrates Picture This 5. Identify Circle any words in the diagram that you do Cnidarians Roundworms Annelids Echinoderms not know. When you have ﬁnished reading this chapter, review the words Sponges Flatworms Mollusks Arthropods you circled and state a characteristic of each one. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 215 After You Read Mini Glossary invertebrates (ihn VUR tuh bruts): animals that do not vertebrates (VUR tuh bruts): animals that have a have a backbone backbone symmetry (SIH muh tree): the way parts of an object are arranged

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence that explains the difference between an animal that has symmetry and one that is asymmetrical.

2. Fill in the table below to describe the common characteristics of animals.

Common Characteristics of All Animals

3. How did writing and answering quiz questions help you remember what you read about animal characteristics and classiﬁcation? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about the characteristics of animals. 216 Invertebrate Animals chapter Classifying Animals 143 section ●2 Invertebrate Animals Benchmarks—SC.H.2.3.1: The student recognizes that patterns exist within and across systems. Also covers: SC.F.1.3.4; SC.F.2.3.1; SC.F.2.3.2; SC.F.2.3.3; SC.G.1.3.2

Before You Read What You’ll Learn ■ how invertebrate On the lines below, list a difference between the way plants animals are identiﬁed and animals get food. ■ the major systems of invertebrate animals ■ how invertebrate animals are alike and different

Read to Learn Study Coach Sticky-Note Discussions Sponges As you read the section, use sticky-note paper to mark Scientist have identified about 15,000 species of sponges. paragraphs you find interesting. Most sponges live in the ocean, although some live in Share the interesting freshwater. Adult sponges remain attached to one place for information with a partner. their lifetime. How does a sponge eat? Sponge bodies are made of two layers of cells. Water containing tiny food particles and oxygen flows through the pores of the sponge. The inner part of a sponge’s body is ●A Organize Make a seven- tab Foldable, as shown below. lined with collar cells. Thin, whiplike structures called Use the Foldable to take notes flagella (flah JEH luh) are attached to the collar cells. The about each type of invertebrate. whiplike movements of the flagella keep water moving through the sponge. Other cells digest the food, carry nutrients to all parts of the sponge, and remove wastes from the sponge. How does a sponge protect itself? Many sponges have soft bodies that are supported by sharp, glass-like structures called spicules (SPIHK yewlz). Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Other sponges have a material called spongin. Spongin is like foam rubber. It makes sponges soft and stretchable. Some sponges have both spicules and spongin to protect their soft bodies.

Reading Essentials 217 How do sponges reproduce? Sponges can reproduce asexually and sexually. A sponge reproduces asexually when a bud on the side of the parent sponge develops into a small sponge. The small sponge breaks off, floats away, and attaches itself to a new surface. New sponges also can grow from pieces of a sponge. Cnidarians Jellyfish, sea anemones, hydra, and coral are cnidarians (nih DAR ee unz). Cnidarians are hollowed-bodied animals with two cell layers that are organized into tissues. Cnidarians have tentacles surrounding their mouths. The tentacles shoot out harpoon-like stinging cells to capture prey. Cnidarians have radial symmetry, so they can locate food that floats by from any direction. The inner cell layer digests the food. Nerve cells work together as a nerve net throughout the cnidarian’s whole body. 1. Explain Why does a How do cnidarians reproduce? cnidarian use stinging cells? Cnidarians reproduce both sexually and asexually. Some cnidarians, such as hydras, reproduce asexually by budding. Some can reproduce sexually by releasing eggs or sperm into the water. The eggs from one cnidarian are fertilized by the sperm from another cnidarian. Flatworms and Roundworms Unlike sponges and cnidarians, flatworms search for food. Flatworms are invertebrates with long, flattened bodies and bilateral symmetry. A flatworm’s body is soft and has three layers of tissue organized into organs and organ systems. Some kinds of flatworms can move around and search for food. These flatworms have a digestive system with one opening. Most flatworms are parasites that live in or on their T FO A C U hosts. A parasite gets its food and shelter from its host. C

S F Benchmark Check Roundworms are the most widespread animal on Earth. SC.H.2.3.1 There are thousands of kinds of roundworms. Billions of roundworms can live in an acre of soil. ✔ 2. Identify What type of symmetry do A roundworm’s body is a tube inside a tube. Between the

flatworms have? two tubes is a cavity full of fluid. The fluid-filled cavity Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright separates the digestive tract from the body wall. The digestive tract of a roundworm has two openings. Food enters the roundworm through the mouth, it is digested in a digestive tract, and wastes exit through the anus.

218 Classifying Animals Mollusks A mollusk is a soft-bodied invertebrate that usually has a shell. A mollusk also has a mantle and a large, muscular foot. The mantle is a thin layer of tissue that covers the mollusk’s soft body. The foot is used for moving or for holding the animal in one place. Snails, mussels, and octopuses are mollusks. Mollusks that live in water have gills. Gills are organs in which carbon dioxide from the animal is exchanged for oxygen from the water. Mollusks that live on land have lungs in which carbon dioxide from the animal is exchanged for oxygen from the air. What body systems does a mollusk have? A mollusk has a digestive system with two openings. Many mollusks have a scratchy, tonguelike organ called the radula (RA juh luh). The radula has rows of tiny, sharp teeth that the mollusk uses to scrape small bits of food off rocks and other surfaces. Some mollusks have an open circulatory system, which 3. Define What is a radula? means they do not have blood vessels. Instead, the blood washes over the organs, which are grouped together in a fluid-filled cavity inside the animal’s body. Others have a closed circulatory system in which blood is carried through blood vessels. Segmented Worms Earthworms, leeches, and marine worms are segmented worms. Segmented worms are also called annelids (A nul idz). A segmented worm’s body is made up of repeating rings that make the worm flexible. Each ring or segment has nerve cells, blood vessels, part of the digestive tract, and the coelom (SEE lum). The coelom is a body cavity that separates the internal organs from the inside of the body wall. A segmented worm has a closed circulatory system and a complete digestive system with two body openings. What do earthworms eat? 4. Identify What is another name for segmented Earthworms are important in shaping the landscape. They worms?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright move through soil by eating the soil. The earthworm uses the organic matter in the soil for food. The undigested wastes and soil that leave the earthworm make the soil better. Earthworms add nutrients to the soil and loosen it. This increases the fertility of the soil.

Reading Essentials 219 Arthropods Scientists have discovered more than a million species 5. Infer Like arthropods, you have appendages. Name of arthropods (AR thruh pahdz). An arthropod is an two human appendages. invertebrate animal with jointed appendages (uh PEN dih juz). Appendages are structures such as claws, legs, or antennae that grow from the body. Arthropods have bilateral symmetry and segmented bodies similar to annelids. Most arthropods have fewer and more specialized segments. They have an open circulatory system. Oxygen enters the animal’s tissues through spiracles. Fertilization in most arthropods is internal. How does an arthropod protect itself? Arthropods have hard body coverings called exoskeletons. The exoskeleton protects and supports the animal’s body and reduces water loss. As the animal grows, it sheds the exoskeleton, which does not grow with the animal. What is metamorphosis? The young of many arthropods don’t look anything like the adults. Many arthropods completely change their body form as they grow. This change in body form is called metamorphosis (met uh MOR fuh sus). Butterflies, bees, and beetles are arthropods that go through a complete metamorphosis. Complete metamorphosis has four stages—egg, larva, pupa (PYEW puh), and adult. At each stage, the arthropod looks completely different. Some insects such as grasshoppers and dragonflies go through incomplete metamorphosis. They have only three stages—egg, nymph, and adult. The nymph looks similar to its parents, only smaller. A nymph sheds its exoskeleton by a process called molting as it grows. The two types of metamorphosis are shown in the figure below. Complete Metamorphosis Incomplete Metamorphosis

Picture This Nymph Molt 6. Identify Circle the names Eggs of the stages that are the Adult Nymph same for complete and Egg

Adult Larva Pupa

220 Classifying Animals Echinoderms Echinoderms (ih KI nuh durmz) are animals that have radial symmetry. Sea stars and sand dollars are echinoderms. Echinoderms have spines of different lengths that cover the outside of their bodies. Most echinoderms have an internal skeleton made up of bonelike plates that supports and protects the animal. Echinoderms have a simple nervous system, but no head or brain. Some echinoderms are predators, some are filter feeders, and some feed on decaying matter. What is a water-vascular system? 7. List two examples of echinoderms. An echinoderm has a water-vascular system, which is a network of water-filled canals and thousands of tube feet. The tube feet work like suction cups to help the animal move and capture prey. The figure below shows the parts of a sea star. A sea star eats by pushing its stomach out of its mouth and into the opened shell of its prey. After the prey’s body is digested, the sea star pulls in its stomach. Like some other invertebrates, sea stars can regrow lost or damaged parts.

Anus

Ray

Picture This 8. Explain Highlight the name of the body structure Stomach a sea star uses to capture prey. Mouth Tube feet Radial canal Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 221 After You Read Mini Glossary appendage (uh PEN dihj): a structure such as a claw, leg, metamorphosis (met uh MOR fuh sus): a change in or antennae that grows from the body body form closed circulatory system: a circulatory system in which open circulatory system: a circulatory system without blood is carried through blood vessels blood vessels in which blood washes over the organs exoskeleton: a hard body covering that protects and supports the body and reduces water loss

1. Review the terms and their deﬁnitions in the Mini Glossary. Write a sentence that describes how an arthropod might use an appendage.

2. Complete the ﬂowcharts to compare complete and incomplete metamorphosis.

Complete Metamorphosis

1. 2. 3. 4.

Incomplete Metamorphosis

1. 2. 3.

3. How do the sticky-notes help you remember what you have read? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about arthropods and echinoderms. 222 Classifying Animals chapter Classifying Animals 00143 section ●3 Vertebrate Animals Benchmarks— SC.F.1.3.1: The student understands that living things are composed of major systems that function in reproduction, growth, maintenance, and regulation. Also covers: SC.F.1.3.4; SC.F.2.3.1; SC.F.2.3.3; SC.G.1.3.2; SC.H.1.3.3; SC.H.1.3.6

Before You Read What You’ll Learn ■ the classiﬁcation of List three animals on the lines below. Then write one thing vertebrate animals that all these animals have in common with humans. ■ the systems of vertebrate animals ■ the difference between vertebrate animals

Read to Learn Study Coach Create a Quiz Write a What is a chordate? question about the main idea under each heading. Exchange Familiar animals such as birds, fish, cats, and dogs belong quizzes with another student. to a large group of animals called chordates. Chordates Together discuss the answers to (KOR dayts) are animals that have the following three the quiz questions. characteristics—a notochord (NOH tuh cord), a nerve cord, and pharyngeal (fur RIN jee uhl) pouches at some time during their development. The notochord is a flexible rod that runs the length of the developing organism. The nerve cord is made of nerve tissue. In most chordates, one end of the nerve cord develops into the organism’s brain. Pharyngeal pouches are slitlike openings between the inside of the body and the outside of the body. They are present only in the early stages of the organism’s development. In some chordates, like the lancelet in the ●B Define Use a quarter figure below, the pharyngeal pouches develop into gill slits. sheet of notebook paper, as shown below, to define the key Nerve cord Gill slits words in this section—chordate, ectotherm, endotherm, and

Movement Chordate of water Ectotherm Endotherm Cartilage

Reading Essentials 223 What are the characteristics of vertebrates? Chordates are classified into several smaller groups. The largest group of chordates is made up of the vertebrates, which include humans. All vertebrates have an internal system of bones called an endoskeleton. The endoskeleton supports and protects the body’s internal organs. For example, the skull is the part of the endoskeleton that surrounds and protects the brain. How do vertebrates control body temperature? Vertebrates are either ectotherms or endotherms. ●C Identify Make a two-tab Foldable, as shown below. Ectotherms (EK tuh thurmz) are cold-blooded animals. Identify the characteristics of Their body temperature changes as the temperature of their ectotherms and endotherms. surroundings changes. Fish and reptiles are ectotherms. Endotherms (EN duh thurmz) are warm-blooded animals. Their body temperature does not change with the Ectotherms Endotherms surrounding temperature. Humans are endotherms. Your body temperature is usually about 37°C, but can vary by about 1°C, depending on the time of day. Fish Fish are the largest group of vertebrates. Scientists classify fish into three groups—bony, jawless, and jawed cartilaginous (kar tuh LA juh nuhs). All fish are ectotherms and live in water. Some species of fish are adapted to live in freshwater and other species are adapted to live in salt water. Fish have gills. Gills are fleshy filaments where carbon dioxide and oxygen are exchanged. Water that contains oxygen passes over the gills. When blood is pumped into the gills, the oxygen in the water moves into the blood. At the same time, carbon dioxide moves out of the blood in the gills and into the water. 1. Explain the purpose of Most fish have pairs of fanlike fins. Fish use fins to steer, fish gills. balance, and move. The motion of the tail fin pushes the fish through the water. Most fish have scales. Scales are thin structures made of a bony material that overlap to cover the skin. Amphibians Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Amphibians (am FIH bee unz) are animals that spend part of their lives in water and part on land. They have many adaptations that allow for life both on land and in the water. Amphibians include frogs, toads, salamanders, and newts.

224 Classifying Animals What are characteristics of amphibians? Amphibians are vertebrates with a strong endoskeleton made of bones. The skeleton helps support their body while 2. Describe two on land. characteristics that allow amphibians to live on land. Adult amphibians use lungs instead of gills to exchange oxygen and carbon dioxide. Lungs are an important adaptation for living on land. Amphibians have three- chambered hearts, in which blood carrying oxygen mixes with blood carrying carbon dioxide. This mixing makes less oxygen available to the amphibian. Adult amphibians also exchange oxygen and carbon dioxide through their moist skin, which increases their oxygen supply. Amphibians can live on land, but they must stay moist for the exchange of oxygen and carbon dioxide to occur. Amphibian hearing and vision also are adapted to life on land. Amphibians have tympanums (TIHM puh nuhmz), or eardrums, that vibrate in response to sound waves. Large eyes help some amphibians catch their prey. Land environments provide many insects as food for adult amphibians. They have long, sticky tongues used to capture the insects. How do amphibians develop? Most amphibians go through a series of body changes called metamorphosis (me tuh MOR fuh sus). Eggs are most often laid in water and hatch into larvae. Young larval Picture This forms of amphibians live in water. They have no legs and 3. Compare Circle the breathe through gills. Over time, they develop the body stage of metamorphosis in which frogs are most like structures needed for life on land including legs and lungs. ﬁsh. The rate of metamorphosis depends on the species, the water temperature, and the amount of available food. The ﬁgure below shows the stages of development for one amphibian—the frog.

Stage 2: Fertilized frog eggs are hatched into tadpoles. Tadpoles live in water. They use their gills for gas exchange.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Stage 4: The adult frog can live and move about on land.

Stage 1: Frog eggs Stage 3: Tadpoles begin to grow into are laid and fertilized. adults. They develop legs and lungs.

Reading Essentials 225 Reptiles Snakes, lizards, turtles, and crocodilians are reptiles. Reptiles are vertebrates and ectotherms. Most reptiles live their entire lives on land and do not depend on water for reproduction. What are some types of reptiles? A turtle is covered with a hard shell. Most turtles can bring their heads and legs into the shell for protection. Alligators and crocodiles are large reptiles that live in or near water. Alligators and crocodiles are predators that live in warmer climates. Lizards and snakes make up the largest group of reptiles. Snakes and lizards have an organ in the roof of the mouth that senses molecules collected by the tongue. The constant in-and-out motion of the tongue allows a snake or lizard to smell its surroundings. Lizards have movable eyelids and external ears. Most lizards have legs with clawed toes on each foot. Snakes move without legs. They don’t have eyelids 4. Identify the largest or ears. Snakes feel vibrations in the ground instead of group of reptiles. hearing sounds. What are some reptile adaptations? A thick, dry waterproof skin is an adaptation that allows reptiles to live on land. Reptile skin is covered with scales to reduce water loss and help prevent injury. Reptiles breathe with lungs. Reptiles that live in water, like sea turtles, must come to the surface to breathe. Two adaptations allow reptiles to reproduce on land— internal fertilization and laying shell-covered eggs. Sperm are deposited directly into the female’s body. Female reptiles lay fertilized eggs that are covered by tough shells. These eggs are called amniotic (am nee AH tihk) eggs. An amniotic egg supplies the embryo with everything it needs to develop. A leathery shell protects the embryo and yolk. The yolk is the embryo’s food supply. When a reptile hatches, it is fully developed.

5. Determine What is the purpose of the yolk in the Birds

amniotic egg? Birds are vertebrates that have two wings, two legs, and a Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright bill or beak. Birds are covered mostly with feathers. They lay eggs with hard shells and sit on their eggs to keep them warm until they hatch. All birds are endotherms.

226 Classifying Animals How do bird species differ? There are more than 8,600 species of birds. Different species have different adaptations. For example, ostriches have strong legs for running. Penguins can’t fly, but they are excellent swimmers. Wrens have feet that allow them to perch on branches. How are birds adapted for flight? The bodies of most birds are designed for flight. They are streamlined and have light, strong skeletons. The inside of a bird’s bones is almost hollow. Special structures make the 6. Infer What features do bones strong, but lightweight. A bird’s tail is designed to airplanes have that are provide the stiffness, strength, and stability needed for flight. similar to birds? Birds use their tail to steer. Birds need a lot of energy and oxygen to fly. They eat high-energy foods like nectar, insects, and meat. They have a large, efficient heart. A bird’s lungs connect to air sacs that provide a constant supply of oxygen to the blood and make the bird more lightweight. Birds beat their wings up and down as well as forward and backward. A combination of wing shape, surface area, wind speed, and angle of the wing provide the upward push needed for flight. What is the function of feathers? Birds are the only animals with feathers. They have two main types of feathers—contour feathers and down feathers. ●D Define Use a quarter- Contour feathers are strong and lightweight. They give adult sheet of notebook paper, as shown below, to define the key birds their streamlined shape and coloring. Contour feathers words in this section—contour have parallel strands, called barbs, that extend from the main feathers and down feathers. shaft. Outer contour feathers on the wings and tail help a Contour bird move, steer, and keep from spinning out of control. feathers Down Feather color and patterns help attract mates. The color feathers patterns also protect birds from predators by helping the birds blend into their surroundings. Birds have down feathers that trap and keep warm air next to their bodies. In adult birds, down feathers provide a layer of insulation under the contour feathers. Down feathers cover the bodies of some young birds. Birds care for their feathers by preening. Birds preen, or Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright use their bills, to clean and rearrange their feathers. During preening, birds also spread oil over their bodies and feathers. The oil keeps the bird’s skin soft and keeps feathers and scales from becoming brittle.

Reading Essentials 227 Mammals Moles, dogs, bats, and humans are some examples of ●E Define Use a quarter- sheet of notebook paper, as mammals. Mammals are vertebrates and endotherms. They shown below, to define the key live in water and in many different climates on land. They words in this section—herbivore, burrow through the ground and fly through the air. carnivore, and omnivore. Mammals have mammary glands in their skin. A mammal’s skin usually is covered with hair that keeps the body from being too hot or too cold. The hair also protects mammals from wind and water. Some mammals, like bears, have thick fur. Other mammals, like humans, have a few patches of thick hair while the rest of the body has little hair. Dolphins have little hair. Porcupines have quills, which are a kind of modified hair. Why do mammals have mammary glands? In females, the mammary glands produce and release milk for the young. For the first few weeks or months of life, the milk provides all the nutrients the young mammal needs. What kinds of teeth do mammals have? Plant-eating animals are called herbivores. Animals that eat meat are called carnivores. Animals that eat plants and meat are called omnivores. Mammals have four types of teeth—incisors, canines, premolars, and molars. As the figure below shows, you usually can tell from the kind of teeth a mammal has whether it eats plants, meat, or both.

Mountain lions are carnivores. Humans are omnivores. They have incisors They have sharp canines that that cut vegetables, premolars that are are used to rip and tear ﬂesh. sharp enough to chew meat, and molars that grind food.

Picture This 7. Identify Circle the teeth that carnivores use to rip and tear ﬂesh. Highlight the teeth that omnivores and herbivores use to cut vegetables. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Herbivores, like this beaver, have incisors that cut vegetation and large, ﬂat molars that grind it.

228 Classifying Animals What body systems do mammals have? Mammals have well-developed lungs made of millions of small sacs called alveoli. Alveoli allow the exchange of carbon dioxide and oxygen during breathing. Mammals also have a complex nervous system that lets them learn and remember more than many other animals. Mammals have larger brains than other animals of similar size. All mammals have internal fertilization. After an egg is fertilized, the developing mammal is called an embryo. Most mammal embryos develop inside the female in an organ called the uterus. Monotremes make up the smallest group of mammals. 8. Apply What kind of They lay eggs instead of having live births. The female fertilization do all mammals monotreme sits on the eggs for about ten days before they have in common? hatch. The mammary glands of monotremes do not have nipples. The milk seeps through the skin onto their fur. The young monotremes lick the milk off the fur. Duck-billed platypuses are an example of monotremes. How do young marsupials develop? Most marsupials, such as kangaroos and koalas, live in Australia. The opossum is the only marsupial native to North America. A marsupial embryo develops for only a few weeks within the uterus. When a marsupial is born, it is not fully formed. It has no hair and is blind. The young marsupial uses its sense of smell to find its way to a nipple usually within the mother’s pouch. It attaches to the nipple to feed and finishes developing in the pouch. How do placental embryos develop? Most mammals belong to a group called placentals. Placentals are named for the placenta, which is a saclike organ that develops from tissues of the embryo in the uterus. An umbilical cord connects the embryo to the placenta. Food and oxygen are absorbed from the mother’s blood. Blood vessels in the umbilical cord carry food and oxygen to the developing young. The blood vessels also take away wastes. In the placenta, the mother’s blood absorbs wastes from the developing young. The blood of the mother and 9. Define What is the the embryo do not mix. gestation period? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright The time of development from fertilization to birth is called the gestation period. Gestation periods vary widely, from about 21 days in rats to about 616 days in elephants. Human gestation lasts about 280 days.

Reading Essentials 229 After You Read Mini Glossary amniotic (am nee AH tihk) egg: the environment for the ectotherm (EK tuh thurm): a cold-blooded animal whose development of a reptile embryo body temperature changes as the temperature of its carnivore: an animal that eats meat surroundings change chordate (KOR dayt): an animal that has, at some time endotherm (EN duh thurm): a warm-blooded animal during its development, three characteristics present— whose body temperature does not change with the a notochord, nerve cord, and pharyngeal pouches temperature of its surroundings herbivore: a plant-eating animal omnivore: an animal that eats plants and meat

1. Review the terms and their deﬁnitions in the Mini Glossary. Write one or more sentences to explain how herbivores, carnivores, and omnivores are different.

2. Complete the table below to list the adaptations birds have for ﬂight.

Adaptations for Flight

1. 4.

2. 5.

3. 6.

3. Complete the diagram below to identify the three types of mammals.

End of Visit ﬂ7.msscience.com to access your textbook, interactive games, Section and projects to help you learn more about mammals.

230 Classifying Animals Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. certain behaviors, and they learn otherbehaviors. learn andthey behaviors, certain Animals are with born organisms anditsenvironment. innat itstailisaresponsedog wagging to your greeting. Your thirst. water isaresponse to the internal stimulus of reacts to astimulus iscalle an way The such ashunger orthirst. can beinternal, of theterritory entering dog Astimulus astimulus. called B Innate Behavior What isastimulus? Behavior such asin-lineskatingorjumpingrope. explain how you anewskill, learned On thelinesbelow, ulsmyb es,itisbuiltcorrectly. builds may bemessy, the firstnestabird Although a nestisaninnate behavior. building For birds, reacts to aninternal orexternal stimulus. donothave to belearned. They section e A behavior that an organism is born with iscalledan with A behavior thatanorganismisborn is thatcausesareaction Anything intheenvironment Animals are different from oneanotherintheirbehavior. Innate behavior patterns occur the firsttimeananimal ha chapter Read toLearn YouBefore Read 00 15 v e b 3 characteristics; reproduction; Benchmarks—SC.F.1.3.7: Also covers: io r e ha is theway other anorganisminteracts with v ● io SC.G.1.3.2; SC.H.1.3.6;SC.H.3.3.3;SC.H.3.3.5 SC.F.2.3.3: 1 SC.H.2.3.1: Animal Behavior r hs ye fbehaviors are inherited. of types These . Types ofBehavior The studentknowsthatgenerallyorganismsinapopulationlivelongenoughtoreproducebecausetheyhavesurvival The studentrecognizesthatpatternsexistwithinandacrosssystems. The studentknowsthatbehaviorisaresponsetotheenvironmentandinfluencesgrowth,development,maintenance, d a response. Getting a drink of Gettingadrink d aresponse. nte aedg Astimulus maledog. another a eetra,such asamale external, can be animal ● answers tothequestions. different colortohighlightthe in thissection.Thenusea Highlight eachquestionhead Identify Main Ideas have observed. behaviors ofananimalthatyou Describe theinnateandlearned Foldable, asshownbelow. A ■ ■ ■ What You’llLearn Describe learned behaviors examples ofdifferent to survive reflexes andinstincts how organismsuse learned behavior between innateand the differences Reading Essentials Behaviors Behaviors Learned Innate Make atwo-tab 231 Why are innate behaviors important? The behavior of animals with short life spans, such as insects, is mostly innate behavior. An insect cannot learn from its parents. By the time the insect hatches, its parents have died or moved on. Innate behavior allows animals to respond quickly. A quick response often means the difference between life and death. 1. Explain Why do insects Reflex actions are the simplest innate behaviors. A reflex mostly have innate is an automatic response that does not involve a message behavior? from the brain. When something is thrown at you, you blink. Blinking is a reflex action. Your body reacts on its own. You do not think about the behavior. What is instinctive behavior? An instinct is a complex pattern of innate behavior. Instinctive behavior begins when an animal recognizes a stimulus. It continues until the animal has performed all parts of the behavior. Spinning a web is an instinctive spider behavior. A spider knows how to spin a web as soon as it hatches. Instinctive behaviors take much more time to complete than reflexes. A spider may spend days building a web. Learned Behavior Animals also have learned behaviors. Learned behavior develops over an animal’s lifetime as a result of experience or practice. Animals with more complex brains have more 2. Which animal Identify learned behaviors. Fish, reptiles, amphibians, birds, and Inc. w-Hill Companies, likely has more learned mammals all learn. behaviors—a spider or a monkey? Why? Learned behavior helps animals respond to changing situations. In changing environments, an animal that can learn a new behavior is more likely to survive than an animal that cannot learn a new behavior. Learned behavior is important for animals with long life spans. The longer an animal lives, the more likely it is that its environment will change. Can instincts change? Learned behavior can change instincts. Key deer instinctively stay away from humans. If humans feed the

deer, the deer learn that humans give food. They learn to a division of The McGra © Glencoe/McGraw-Hill, Copyright approach humans for food. More deer-car crashes could happen as deer walk up to cars. Florida wildlife ofﬁcials post signs to warn people not to feed deer. They want deer to keep their instinctive fear of humans.

232 Animal Behavior Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. sound of a bell even if they were they notfed. abelleven if sound of were dogs The conditioned to salivate atthe food. with thebell connected dogs The thesoundof he fedthedogs. He abellbefore rang asseeninthefigure below. stimulus, Pavlov addedanother seeandsmellfood. when they salivate dogs He knewthathungry conditioning works. Pavlov to anexperiment explain performed how this Russian scientistIvan stimulus before theusualstimulus. stimulus becomes linked adifferent stimulus. with c having to thinkaboutit. you candoitwithout Once you askill, learn a bicycle. andriding your shoes, tying such asfeedingyourself, error, You many and learned through trial skills error learning. recognizing members of their own species. theirown recognizing membersof anotherspecies have difficulty towardimprinted animalsof Animals thatbecome and gettingalongintheworld. protecting themselves, geese have experience infindingfood, becauseadult Thisbehavior isimportant female goose. isanadult usually object moving The it seesafter hatching. goslingfollows A object thefirstmoving orhatching. birth timeafter ashort attachment to within anotherorganism eoeCniinn odtoigAfterConditioning Conditioning Before Conditioning How doesconditioningchangebehavior? learning? What istrial-and-error How doesimprintingoccur? o There are two types of conditioning. One type addsanew Onetype conditioning. There of are two types nml fe er e eair ycniinn.In Animals often newbehaviors by learn conditioning. trial-and- experience iscalled Behavior thatchanges with I ndit mpr io int ning ing , behavior ischanged behavior sothataresponse to one , occurs asocial whenananimalforms Picture This ● the twotypesofconditioning. Use aVenndiagramtocompare tab Foldable,asshownbelow. B 3. Compare respond toabell. conditioned dogsto describing howPavlov partner, taketurns Explain Reading Essentials Stimulus Stimulus Before After Both New New Working witha Make athree- 233 Picture This 5. 4. 234 own experiences. of conditioningfromyour example ofthissecondkind bananas? boxes toreachthe the problembypiling chimpanzee abletosolve Describe Analyze Animal Behavior Give an Why wasthe to solve theproblem. orinsight, Thechimpanzee usedpastexperiences, problem. thechimpanzee must have solved asimilar the past, At sometimein andreached thebananas. climbed them, thechimpanzee piledupboxes foundintheroom, up, giving Instead of achimpanzee’s reach. were placed outof problems. Much of adult human learning isbasedoninsight. adulthuman learning Much of problems. you more often useinsight to solve you grow older, As you to learned solve anderror. problems usingtrial baby, When you were a past experiences to solve newproblems. Another Type ofConditioning How dopastexperienceshelpsolveproblems? a o aedn fyou hadnotbeenoffered areward. may nothave doneif thatyou to activities perform or have beenconditioned, You have learned, because you wantto getyour allowance. You dothechores conditioning. of thistype example of Gettinganallowance fordoingchores isan happened. newstimulus a isgiven after abehavior has conditioning, I bananas In below, theproblem-solving shown experiment nsig ht safr freasoning thatallows animalsto use of is aform In thesecond kindof

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. 2. 1. imprinting: conditioning: behavior: Mini Glossary o i nigasest h usinhashl o er bu ye fbehavior? How of didfindinganswers to thequestionheadshelpyou abouttypes learn animalbehavior. of thedifferent organizer below types with inthegraphic Fill explains thedifference between instinctandinsight. Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After You Read different stimulus a responsetoonestimulusbecomesassociatedwith organisms anditsenvironment within ashorttimeafterbirthorhatching animal formsasocialattachmenttoanotherorganism the wayanorganisminteractswithother a learnedbehaviorthathappenswhenan a wayofchanginglearnedbehaviorsothat Innate behavior of behavior. games, andprojects tohelpyoulearnmoreabout thetypes Visit fl7.msscience.com Types ofAnimalBehavior to accessyourtextbook,interactive reflex: instinct: insight: innate behavior: solve newproblems message fromthebrain spinning aweb an automaticresponsethatdoesnotinvolvea a formofreasoningthatusespastexperiencesto a complexpatternofinnatebehavior,suchas a behaviorthatanorganismisbornwith Reading Essentials Section End of 235 to askandanswerthequestions. other side.Workwithapartner flash cardsandanswersonthe write questionsononesideof you arereadingthissection, ● Make Flash Cards animals. behavioral adaptationsof shown below.Describethree tab conceptmapFoldable,as C section 236 ■ ■ ■ What You’llLearn chapter Describe Study Coach 00 behavior behavior andcyclic the importanceofsocial success improves reproductive how courtshipbehavior behavioral adaptations the importanceof 15 3 characteristics; reproduction; Benchmarks—SC.F.1.3.7: Also covers:

Animal Behavior

of territory of Defense

Behavioral Adaptations Courtship

● behavior 2 SC.G.1.3.2; SC.H.1.3.2;SC.H.1.3.3;SC.H.1.3.4;SC.H.1.3.5;SC.H.1.3.6;SC.H.3.3.2;SC.H.3.3.5;SC.H.3.3.6 SC.F.2.3.3: SC.H.2.3.1: Make athree- Animal Behavior Behavioral Interactions The studentknowsthatgenerallyorganismsinapopulationlivelongenoughtoreproducebecausetheyhavesurvival While The studentrecognizesthatpatternsexistwithinandacrosssystems.

The studentknowsthatbehaviorisaresponsetotheenvironmentandinﬂuencesgrowth,development,maintenance,

behavior Social examples of behaviors thathelpanimalsrecognize possiblemates. animal groupsandmatingare courtship instinctive ritual formost For example, innate behavior patterns canbeseen. complex When otheranimals, ananimalinteracts with is lesslikely to getlostthan animalsthattravel alone. Agroup travel Animals thatmigrate in groups. a lonezebra. than zebras lionsare lesslikely to attackaherd of example, For behaviors Social helpthespeciessurvive. getting food. and protecting each other, claiming territories, the young, for caring andmating, Social behaviors includecourtship Social Behavior Instinctive BehaviorPatterns ways thatyou communicate. listthree other Onthelinesbelow, isby talking. friends One way thatyou communicate your with familyand neatosaogognsso thesamespecies are Interactions amongorganismsof 3. 2. 1. inagroup provides: Living Animals often live ingroups. instinctive behavior. orare with, born Animals inherit, Read toLearn YouBefore Read security whentraveling fromsecurity place to place fromwarmth othergroup members from predatorssafety so cial b e ha v io r . Social behaviors are Social inherited. .

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. What is a society? A society is a group of animals of the same species living and working together in an organized way. Insects, such as ants, live in societies. Each member of the society has a certain role. One female ant lays eggs and a male ant fertilizes the eggs. The workers do all the other jobs in the society. Some animal societies are organized by dominance. The 1. Define What is a society? top animal controls the other members of the society. Wolves live in packs. One female in the pack is dominant. She controls the mating of other females in the pack. This behavior controls the size of the pack and helps the pack survive. Territorial Behavior A territory is an area that an animal defends from other members of the same species. Animals may show ownership of territories by making sounds, leaving scent marks, or attacking members of the same species who enter the territory. Why do animals defend their territories? Territories contain food, shelter, and possible mates. If an animal has a territory, it will be able to mate and produce offspring. Defending territories is an instinctive behavior. It improves the survival rate of an animal’s offspring. How do animals defend their territories? In order to defend their territory, protect their young, or get food, many animals show aggression. Aggression is a forceful behavior used to dominate or control another w-Hill Companies, Inc. w-Hill Companies, animal. Animals of the same species rarely fight to the death. An animal that avoids being attacked by another animal is showing submission. In the figure below, one wolf has rolled over and made itself as small as possible to communicate submission to the dominant wolf.

Reading Essentials 237 Communication Communication is important in all social behavior. Communication is an action by a sender that affects the behavior of a receiver. Animals in a group communicate with sounds, scents, and actions. Alarm calls, chemicals, speech, courtship behavior, aggression, and submission are types of communication. How do animals attract mates? Courtship behavior allows the male and female members of a species to recognize each other. Courtship behaviors

F T OC excite males and females so they are ready to mate at the A U C

S F Benchmark Check same time. The courtship behavior of a male bird of paradise includes spreading its tail feathers and strutting. SC.F.1.3.7 This behavior attracts female birds of paradise. Courtship ✔ 3. Describe the behavior helps increase reproductive success. purpose of courtship In most species, males are more colorful than females. behaviors. The males perform the courtship activities to attract a mate. Some courtship behaviors allow males and females to find each other across distances. How do animals use chemicals to communicate? Ants leave trails that other ants can follow. Male dogs urinate on objects and plants to let other dogs know they have been there. These animals are using chemicals called pheromones (FER uh mohnz) to communicate. A pheromone is a chemical produced by one animal to influence the behavior of another animal of the same Inc. w-Hill Companies, species. Pheromones remain in the environment so that the sender and receiver can communicate without being in the same place at the same time. Males and females use pheromones to set up territories, warn of danger, and attract mates. Some animals release alarm pheromones when hurt or in danger. ●D Identify Make a half- How do animals use sounds to communicate? book Foldable, as shown below. Male crickets rub one forewing against the other to make Write notes to identify ways animals communicate with a chirping sound. The sound attracts female crickets. Each chemicals, sound, and light. species of crickets makes a different sound. Rabbits thump the ground, gorillas pound their chests, frogs croak, and a division of The McGra © Glencoe/McGraw-Hill, Copyright beavers slap the water with their flat tails. These sounds Communication among organisms are forms of communication to other animals of the same species.

238 Animal Behavior Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chance forsurvival. reproduce inenvironments thatgive abetter theiroffspring mig Thisinstinctive seasonalmovement iscalled change. called luminescent substance thathelpsthemescapetheirpredators. a clouds of give shrimp Deep-sea off prey. animals attract Bioluminescence helpssome doesnotreach. where sunlight bioluminescence to communicate. andbeetlesuse organisms, marine flies, kindsof Certain flashing. Each pattern hasitsown of species possible mate. to locate light a a flashof A firefly gives off organism’s body. isproducedlight through chemical reactions inthe The called bioluminescence (biohlewmuh NEHsunts). otra nh U u) Owlsare nocturnal. (nahkTURnul). nocturnal Animals thatare active are atnight (dydiurnal URnul). Animals thatare active theday during are circadian rhythm. sleepingandwakefulness calleda have a24-hourcycle of Most animals in response to changes intheenvironment. What ismigration? What ishibernation? Cyclic Behavior otherusesofbioluminescence? What are How islightusedtocommunicate? sarsos oeteeha,lc ffo,or drought. food, lackof as aresponse to extreme heat, animalsdothis Desert reduced calledestivation. activity of reptiles hibernate. mammalsandmany Some amphibians and in thespring. body fatandstay inactive untiltheweather becomes warm ontheirstored survive Animals inhibernation slows. rate Theanimal’s breathing itssurroundings. to nearthatof ananimal’s body temperature drops hibernation, During responds to cold temperatures andalimited foodsupply. Many animalsmove to newlocations whentheseasons H Innate behavior thathappensinarepeating pattern is Many bioluminescent animalsare founddeepinoceans is light to things give living certain off of The ability ndsrlk niomns someanimalsgointo aperiod In desertlike environments, r ib at e cy io r nat c n lic b . io Most to find foodorto animalsmigrate n e ha is acyclic behavior inwhich ananimal v io r hstp fbehavior isoften repeated of type This . animals. cyclic behaviorsfoundinmany shown below,toexplaintwo sheets ofnotebookpaper,as ● E 4. Explain Define bioluminescence? Hibernation Reading Essentials What is Use quarter- Migration 239 2. 1. hibernation: cyclic behavior: courtship behavior: aggression: Mini Glossary ______240 organizer below. animalcommunication inthegraphic Write you onefact of abouteach form learned theterms to explain how innate animal behavior helpsspeciessurvive. of Write asentence usingone Review the terms andtheirdefinitionsintheMini Glossary. After You Read Section limited foodsupplies same time excite eachothersotheyarereadytomateatthe members ofaspeciestorecognizeeachotherand another animal eetn pattern repeating End of Courtship behavior Animal Behavior a forcefulbehaviorusedtodominateorcontrol a cyclicresponsetocoldtemperaturesand innate behaviorthatoccursina behaviors thatallowmaleandfemale ______Chemical communication Forms ofAnimalCommunication ______society: social behavior: pheromone (FERuhmohn): migration: Sound communication interactions. games, andprojectstohelpyou learnmoreaboutbehavioral Visit aespecies same working togetherinanorganizedway the samespecies animal toinfluencethebehaviorofanother fl7.msscience.com a groupofanimalsthesamespecieslivingand instinctive seasonalmovementofanimals interactions amongorganismsofthe to accessyourtextbook,interactive ______a chemicalproducedbyone Light communication

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. environment are called the physical features of Thenonliving, environment. thenonliving without andanimals cannotsurvive Plants Photosynthesis usesCO lv,are called alive, or were once theenvironment that are alive, The features of organisms thatlive there. Thesefactors often determine thekindsof and climate. temperature, soil, sunlight, water, Abiotic factors includeair, photosynthesis to produce food. theirown Organisms such asplantsuse make sugar molecules. to Air Factors Environmental theplantandanimallifearounddoes itaffect you? How would you theclimate where describe you live? How for supporting life. for supporting thesegasesare important Some of othergases. amounts of and trace 0.03percent dioxide, carbon 0.94 percent argon, 21percent oxygen, 78percent nitrogen, is madeupof section Biotic factors are needed forlife. nottheonlythings The air that surrounds Earth iscalledthe The airthatsurrounds Earth dependononeanotherforfoodandshelter. things Living Carbon dioxideCarbon (CO chapter Read toLearn YouBefore Read 00 16 3 Also covers: within andacrosssystems. their Benchmarks—SC.G.1.3.4 AnnuallyAssessed: environments resultintheflowofenergyandcyclingmatterthroughoutsystem; ● SC.B.1.3.1; SC.D.1.3.4;SC.G.2.3.2;SC.H.1.3.4 1 The NonlivingEnvironment biot Abiotic Factors ic (bi AH tihk) factors. tihk) (bi AH 2 abiot ) is necessary forphotosynthesis. ) isnecessary 2 , water, and energy from sunlight andenergy water, , ic (ay bi AH tihk)factors. The studentknowsthattheinteractionsoforganismswitheachotherandnon-livingparts at mosp he r e .Air SC.H.2.3.1: The student the section. summarizes themainpointof beside eachmainheadingthat Summarize 1. ■ ■ ■ What You’llLearn List needed forphotosynthesis? recognizes thatpatternsexist life inanecosystem how climateinfluences that areneededforlife the componentsofair ecosystems factors inmost the commonabiotic Reading Essentials What threethingsare Write aphrase 241 Cellular Respiration Oxygen is released into the atmosphere during photosynthesis. Cells use oxygen to release the chemical energy stored in sugar molecules. This process, called cellular respiration, provides cells with the energy needed for all life processes. Water Water is necessary to life on Earth. It is a major part of the fluid inside the cells of all organisms. Most organisms are 50 percent to 95 percent water. Processes such as cellular respiration, digestion, and photosynthesis occur only if water is present. Environments that have plenty of water usually have a greater variety of and a larger number of organisms than environments that have little water. Soil Soil is a mixture of mineral and rock particles, the 2. Recognizing Cause and Effect How does remains of dead organisms, water, and air. Soil is the top soil affect plant life in an layer of Earth’s crust where plants grow. It is formed partly area? of rock that has been broken down into tiny particles. Soil, an abiotic factor, is made mostly of nonliving rock and mineral particles. But soil also contains living organisms and the remains of dead organisms. The decaying matter in soil is called humus. Soils contain different combinations of sand, clay, and humus. The kind of soil in a region affects the kinds of plants that grow there. w-Hill Companies, Inc. w-Hill Companies, Sunlight Sunlight is the energy source for almost all life on Earth. Plants and other organisms that use photosynthesis are called producers. They use light energy from the Sun to produce their own food. Organisms that cannot make their own food are called consumers. Energy is passed to consumers when they eat producers or other consumers.

3. Identify What are two Temperature types of energy the Sun provides? Sunlight provides the light energy for photosynthesis and

the heat energy for warmth. Most organisms can live only if a division of The McGra © Glencoe/McGraw-Hill, Copyright their body temperatures are between the freezing point of water, 0°C, and 50°C. The temperature of a region depends partly on the amount of sunlight it gets. The amount of sunlight depends on the area’s latitude and elevation.

242 The Nonliving Environment Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. lmts The climates. Thesetwo citieshave different Snow never falls. below 5°C. temperatures go rarely winter Florida, In Key West, month. as tendstemperature elevations to athigher becooler. theair there are elevations, fewer airmoleculesathigher Because heatstheairmolecules. sunlight when warmer Air becomes elevations. atmosphere isthinnerathigher The Earth’s theSun’s atmosphere traps heat. temperature. overThis spreads theenergy alargerarea. nearthepoles. atanangle hitsEarth Sunlight directly. Earth hits sunlight Near theequator, Look atthefigure below. temperatures thanplaces atlatit fromPlaces theequator have farther generally colder Theequator ishalfway between thepoles. latitude. between linesthatcircle polesareThe parallel Earth linesof Climate temperature? How doeselevationaffect temperature? How doeslatitudeaffect rohrpeiiain andwind. or otherprecipitation, rainfall Climate includes temperature, conditions over time. oso somemountainsare socold thatnoplantsgrow there. tops of The Onlylow-growing plantsexist above thetimberline. grow. In Fairbanks, Alaska, winter temperatures winter may beaslow Alaska, In Fairbanks, The timberlineistheelevation affectsits ordistance above sealevel, A region’s elevation, isaffected aregion by itslatitude. The temperature of to locate onEarth points. grid Scientists useanimaginary 2C oeta n ee fsnow fallinone might More thanonemeter of 52°C. c limat e fanarea isitsaverage weather of udesto nearer above which trees donot theequator. Picture This 4. 5. hitting Earthnearthepoles. to highlightthesunlight equator. Useanothercolor hitting Earthdirectlyatthe highlight thesunlight lower elevations? than theairtemperatureat elevations usuallycooler temperature athigher Identify Explain Reading Essentials Why istheair Use onecolorto 243 Picture This 7. 6. 244 of therainshadoweffect. arrows fortheexplanation of thefirstandfourth below, completethelabels Explain things? climate formostliving most importantpartsof Determine The NonlivingEnvironment Ocean Moist On thefigure What arethe as itrises Air cools every year isprobablyevery forest. atropical rain rain cmof the sameaverage temperature andmore than300 An area with per year probably hascactusplantsgrowing there. rain cmof 25°Candgetslessthan25 average temperature of area thathasan an For example, organisms thatlive inanarea. affectthekindsof They climate things. formostliving of parts ecvrdwt oet,whiletheothersideisadesert. be covered forests, with themountaincould onesideof As aresult, less precipitation. shadow rain andreceives much themountainisina side of Theother The asitflows airwarms the mountain. down drier itsmoisture. ithaslostmostof themountain, top of By thetimeaircrosses over the orsnow. in itfallsasrain themoisture When aircools, itcools. air moves to thetop, As the themountain. isforcedwind upward by theslopeof The toward moist airiscarried landby thewind. shows, This movement creates aircurrents thatare calledwind. Colder airsinksbelow airandpushesitupward. warmer thancold airislighter warm air. So, apart. spread farther themolecules As thetemperature increases, gas molecules. Air ismadeupof from theSunheat energy causeswind. How does climate affect life inanarea? How doesclimateaffect What istherainshadoweffect? windscreated? How are Forest Temperature andprecipitation are thetwo mostimportant onan a fetrifl atrs As thefigure below Mountains patterns. canaffectrainfall the anarea, In additionto thetemperature affecting of loses moisture Colder air becomes Cool, dryair Desert

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 2. 1. tihk): biotic (biAH atmosphere: tihk): abiotic (aybiAH Mini Glossary Climate Temperature Sunlight ImportancetoLife Soil Water Air Abiotic Factor Complete below thechart to identifyaway to thateach life. abioticfactor isimportant explains thedifference between abioticandbioticfactors. Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After You Read temperature, andclimate the environment,includingair,water,sunlight,soil, alive orwereonce the airthatsurroundsEarth features oftheenvironmentthatare nonliving, physicalfeaturesof games, andprojectstohelpyou learnmoreaboutabioticfactors. Visit fl7.msscience.com to accessyourtextbook,interactive soil: climate: and wind including temperature,rainfallorotherprecipitation, dead organisms,water,andair a mixtureofmineralandrockparticles,theremains an area’saverageweatherconditionsovertime, Reading Essentials Section End of 245 Picture This Outline heading inthesection. with theinformationundereach outline. Completetheoutline as themainheadingsin the mainheadingsinsection information inthesection.Use outline tosummarizethe section 1. 246 ■ ■ ■ What You’llLearn chapter Study Coach 00 Explain on Earth how nitrogenaffectslife about thecarboncycle is important why Earth’swatercycle food, water,andair. without anyoneadding the fishintanksurvive 16 3 Also covers: within andacrosssystems. their Benchmarks—SC.G.1.3.4 AnnuallyAssessed: The NonlivingEnvironment environments resultintheflowofenergyandcyclingmatterthroughoutsystem; As youread,makean ● to apartnerhow 2 SC.D.1.3.3; SC.D.1.3.4;SC.G.1.3.5;SC.G.2.3.3;SC.G.2.3.4 The NonlivingEnvironment Cycles inNature materials arematerials constantly beingrecycled. These neededforlife. andothermaterials oxygen, nitrogen, carbon, water, amountof hasonlyacertain Earth biosphere. arebecause thematerials recycled. Theorganismsinthisclosedenvironment cansurvive die. decompose Bacteria thoseorganismsthat plants andalgae. wastes The the from thefishandsnailsfertilize the oxygen. Thefishandsnailseattheplantsalgaetake in tank. alsosupplyoxygen They to the through photosynthesis. and air?Theplantsalgaeproduce food theirown water, How addingfood, without survive cantheorganisms canenter. Thetankissealedsothatonlylight and bacteria. The CyclesofMatter thepotwhenyou remove it? do you seeonthelidof What you happenswhen boilwater inacovered pot? What The studentknowsthattheinteractionsoforganismswitheachotherandnon-livingparts The environment issimilarto Earth’s intheaquarium algae, plants, snails, fish, water, with anaquarium Imagine Read toLearn YouBefore Read SC.H.2.3.1: The student recognizes thatpatternsexist

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. returned to theenvironment from animalwastes. Water is Animals release water exhale. vaporasthey puhRAYa process (trans astranspiration known shun). It enters theatmosphere from plantsin andoceans. streams, lakes, Water from evaporates thesurfaces of atmosphere. andenters the water called vapor, water changes into agas, they fall to orotherprecipitation. fall theground asrain they When thedroplets become largeandheavy enough, clouds. Thedroplets jointogether to form tinyand forms droplets. the water evaporates. changing fromchanging to agas aliquid iscalled process The of water. toenough change back into liquid thewater vapor becomes cool Over time, water drops. vapor the temperature The of come into colder contact air. with What iscondensation? The Water Cycle atmosphere andbackto thesurface again. to the Earth howdescribes water moves from thesurface of stefiueblwsos the As thefigure below shows, dustintheair of The water vapor condenses on particles After water vaporenters the water onasunny windowsill, When you leave of aglass Transpiration E v ap o r at atmosphere, eventually itwill eventually atmosphere, io n wat takes place whenliquid e r cy c Groundwater o c le nd Condensation is amodelthat e nsat io n . ● Picture This nitrogen cycles. describe thewater,carbon,and below. UsetheFoldableto tab bookFoldable,asshown A 2. Describe h ae cycle. water the missingprocessesin the figurebylabeling the Identify Reading Essentials nitrogen carbon water Complete Make athree- 247 Picture This 4. 3. 248 Discuss Analyze ways youusewater. cycle? animals playinthenitrogen The NonlivingEnvironment of certainplants. bacteria thatliveontheroots lightning orbynitrogen-fixing into usablecompoundsby Nitrogen gasischanged What isonerole List someofthe compounds tothesoil. wastes returnsomenitrogen Animals eatplants.Animal is shown inthefigureis shown below. available to plantsandanimals. water returns to theatmosphere by limitingtheamountof Humans alsoinfluence how much water atmosphere. water into thatevaporates the can reduce theamountof Using thiswater andfarms. businesses, use intheirhomes, called Through aprocess elements to nitrogen compounds. form cannot usenitrogen directly from theair. mostorganisms However, plentiful gasintheatmosphere. Nitrogen isthemost allorganisms. take place inthecells of Proteins are neededforthelifeprocesses that proteins. of part How do humans affect the watercycle? How dohumansaffect The Nitrogen Cycle The Nitrogen atmosphere iscalledthe andbackto the to organisms, living atmosphere to thesoil, nitrogen from the of transfer This the soiloratmosphere. thenitrogen intheirbodiesreturns to dead organismsdecay, When needbynitrogen they eatingplantsorotheranimals. Animals getthe nitrogen compounds through theirroots. Plantstake inthese nitrogen compounds thatplantsneed. uastk ae rmrsror,rvr,andlakes to rivers, Humans take water from reservoirs, Plants neednitrogen other thathasbeencombined with It isanecessary Nitrogen to things. allliving isimportant nit r o g compounds backintothesoil. decompose, releasingnitrogen Animals andplantsdie e n fi xat io n , some types of soil bacteria form the form soilbacteria of types some , nit r o compounds tobuildcells. Plants usenitrogen g e n cy c le . The nitrogen The cycle .

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. They useCO They atmosphere as carbon dioxideatmosphere ascarbon gas(CO soilhumus andisfoundinthe of ispart Carbon organisms. plants andaddnitrogen compounds to thesoil. supplynitrogen Thesebacteria compounds to the bacteria. have nodulesthatcontain roots nitrogen-fixing with such aspeas, Someplants, plants. certain or intheroots of Most nitrogen-fixing live bacteria on nitrogen-fixing crops. make itmore fertile. canbeaddedto They soilto compounds thatplantscanuse. Compost andanimalmanure alsocontain nitrogen nitrogen. Fertilizers canbeusedto replace soil could become infertile. thesoil thenitrogen compounds are notreplaced, If the soil. in thefieldto decay andreturn theirnitrogen compounds to Theplantsare notleft theplantmaterial. remove therest of often farmers After crops are harvested, place inthesoil. and nonliving world.and nonliving how moleculesmovedescribes carbon between theliving The CarbonCycle soilnitrogen? How dohumanactivitiesaffect to rise. heat from theSun andcauseaverage temperatures onEarth atmosphere is increasing. The extra CO extra The atmosphere isincreasing. The two processes helprecycle onEarth. carbon releases CO Cellularrespiration usesoxygen and in cells. releases energy cellular respiration—theduring chemical process that isreleased from Energy thesemolecules sugar molecules. o xml,we oslfesaebre,CO whenfossilfuelsare burned, For example, uigpooytei.Teaon fCO The amount of photosynthesis. during these purposes cannotremovethese purposes CO Trees thatare for cutdown wood forbuildingandfuel. People alsouse into theatmosphere asawaste product. abnaosaefudi h oeue fliving atoms areCarbon foundinthemoleculesof Another way to replace soilnitrogen isby growing thenitrogen cycle thattakes Humans of canaffectthepart Producers take CO Human alsorelease activities CO 2 Photosynthesis usesCO . 2 , water, and sunlight to make andsunlight energy-rich water, , 2 from photosynthesis. theairduring 2 2 from theatmosphere into theatmosphere. 2 2 and releases oxygen. .The ). 2 could trap morecould trap 2 in the car 2 is released b o n cy c le SC.G.1.3.4 ✔ FC 5. A T

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U U S S Explain Benchmark Check Annually Assessed Reading Essentials two waystoadd a car’s 249 2. 1. nitrogen cycle: evaporation: condensation: carbon cycle: Mini Glossary 250 ntedarm listtheprocesses inthe nitrogen cycle intheorder occur. inwhich they In thediagram, explains thedifference between condensation andevaporation. Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section liquid into watervaporandenterstheatmosphere move betweenthelivingandnonlivingworld the atmosphere atmosphere tothesoil,livingorganisms,andback End of The NonlivingEnvironment process thatoccurswhenliquidwaterchanges a modelthatdescribeshowcarbonmolecules process thatoccurswhenagaschangesto the transferofnitrogenfrom Nitrogen Cycle water cycle: nitrogen fixation: nature. games, andprojectstohelpyou learnmoreaboutthecyclesin Visit fl7.msscience.com surface again the surfaceofEarthtoatmosphereandback bacteria formthenitrogencompoundsthatplantsneed a modelthatdescribeshowwatermovesfrom process inwhichsometypesofsoil to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. deep inEarth’s crust. extremely hotfrom thatlies molten contact magma with water The from thesevents is intheoceandeep cracks floor. Hydrothermal vents are near powerful hydrothermal vents. live They producers live intotal deepunderwater darkness. energy. stored Fats andproteins alsocontain theproducer’s body. of to buildcomplex carbohydrate moleculesthatbecome part are Some used sugar moleculesare broken asenergy. down these Someof insugar molecules. into thechemical energy conversion to lifeonEarth. all isimportant This but itisconverted from to oneform another. recycled, isnot Energy matter requires energy. recycling The of over. Matter canberecycled over and world indifferent ways. Matter move andenergy through thenatural need energy. What are hydrothermal vents? hydrothermal What are duringphotosynthesis? converted How isenergy Energy Converting energy? Why doyou needenergy? What isyour source of section oepouesd o eyo ih o nry These Some producers forenergy. donotrely onlight producers convert energy light photosynthesis, During things living andall matter, are things All living madeof chapter Read toLearn YouBefore Read 00 16 3 Also covers: matter throughoutthesystem; that theinteractionsoforganismswitheachotherandnon-livingpartstheirenvironmentsresultinflowene Benchmarks—SC.B.1.3.4: ● 3 SC.B.1.3.1; SC.D.1.3.3;SC.H.1.3.1;SC.H.1.3.2;SC.H.1.3.4;SC.H.1.3.6;SC.H.1.3.7;SC.H.2.3.1;SC.H.3.3.5 The NonlivingEnvironment Energy Flow The studentknowsthatenergyconversionsarenever100%efficient; SC.G.1.3.4 AnnuallyAssessed: energy. and chemosynthesistoconvert producers usephotosynthesis below, tocomparehow two-tab Foldable,asshown ● Locate Information words. text thathelpsyoudefinethe and underlinethepartof section, reviewthecircledwords define. Attheendofeach and circleanywordyoucannot all theheadingsforthissection B What You’llLearn ■ ■ ■ Compare levels inafoodchain available atdifferent how muchenergyis through ecosystems how energyflows energy-rich compounds how organismsmake Photosynthesis rgy andthecyclingof Reading Essentials The studentknows Chemosynthesis Make a Read 251 Picture This 2. 1. 252 organism onthefoodchain. or Consumerbeloweach chemosynthesis? of organismsuse Identify Explain The NonlivingEnvironment What type Write Producer c moleculesfrom nutrient chemicals iscalled energy-rich of production The useto bacteria make food. theirown that Scientists have thatthehotwater learned hasnutrients organisms thatlive from there sunlight. cannotgetenergy osmr r h hr n ihrseso food chains. consumers are steps thethird of andhigher Animals thateatother producers are thesecond step. thateat such asherbivores, Animals, chemosynthesis. make foodusingeitherphotosynthesis theirown or Allproducers are thefirststep inafoodchain. as plants, such Producers, passfrom oneorganismtoenergy another. organism to organism. andmatter from are transferred energy Throughout nature, from oneorganismtothose moleculesistransferred another. thematter thatmakes up At thesametime, into heat. energy the oritcantransform forgrowth, It canusetheenergy food. stored Thatorganismcanrelease theenergy inthe organism. to another oneorganismistransferred in themoleculesof thatisstored energy The eating producers orotherconsumers. by obtainenergy they Instead, cannot make food. theirown Consumers from oneorganismtocan betransferred another. What ischemosynthesis? How does energy flowinfoodchains? How doesenergy Transfer Energy chemosynthetic bacteria for nutrients andenergy.chemosynthetic fornutrients bacteria live inhydrothermal vent communities rely on that he eas ulgtde o ec epoenrgos the doesnotreachBecause sunlight deepocean regions, The foodchain inthe figure below shows how matter and It also canbeconvertedEnergy from to oneform another. Berries mosynthesis kemhSH hhss.Consumers (kee mohSIHNthuh sus). Mouse Black Bear

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. feeding level is transferred to level. thenextfeeding level higher istransferred available ateach theenergy percent of only about10 fact, In each level becomes smaller. one level to another, isreduced As from theenergy organisms. largest number of largest level andthe becauseit contains themostenergy It isthefirstand below includesallproducers. pyramid the bottom The of at each feedinglevel inanecosystem. reduced asyou move from onelevel to thenext. is available energy linksislimited becausetheamountof of many different foodchains. web ismadeupof Afood relationships inacommunity. amongtheorganisms f A iseaten by many Bladderwort different organisms. fish. and frogs, eatherons, alligators For example, community. How does available energy decline? How doesavailableenergy Pyramids Energy foodwebs? What are took in from the Sun wasuse to transfers rmoelvlo afoodchain to another. from onelevel of isreduced available energy amountof The even lessenergy. Ahawk thateatsthemousegets asheat. the isgiven off energy Someof andgrowth. digestion, as cellular respiration, such from processes, theseedforitsown mouse usesenergy o o hnamueet ed,energy stored in When amouseeatsseeds, Thenumber Most food chains have three to five links. There are many feedingrelationships inawetlands An An d w e e ne b r is amodelthatshows thepossiblefeeding all g y p the mouse. But most of the energy theplant theenergy But mostof the mouse. y r amid shows the amount of energy available energy shows theamountof d tohe Carnivores Herbivores lp the Producers ln rw The plant grow. the seeds carnivores. producers, toherbivores, identify theflowofenergyfrom Foldable, asshownbelow,to ● C 3. Identify consumers? there moreproducersthan Synthesize Producers Herbivores Carnivores Reading Essentials Make apyramid Why are 253 3. 2. 1. energy pyramid: thuhsus): chemosynthesis (keemohSIN Mini Glossary 254 o i nigdfiiin fwords you didnot know flow? helpyou understand energy How didfindingdefinitionsof insect. bird, plant, mountainlion, chain: steps would inwhich they appear inafood intheorderPlace organisms of thefollowing the process works. moleculesareexplains how produced asentence energy-rich andwrite explaining how Choosetheterm that Review theterms andtheirdefinitionsintheMini Glossary. After You Read Section available ateachfeedinglevelinanecosystem chemicals production ofenergy-richnutrientmoleculesfrom End of The NonlivingEnvironment a modelthatshowstheamountofenergy the food web: games, andprojectstohelpyou learnmoreaboutenergyflow. Visit fl7.msscience.com relationships amongtheorganismsinacommunity a modelthatshowsallthepossiblefeeding to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. ol r oet w-hrso Earth’s landspecies. world are hometo two-thirds of the The tropical of regions moistclimates. located inwarm, Ecosystems thathave biodiversity are thehighest usually where temperatures tend to bewarmer. the equator, discover biodiversity thatspecies isgreat. hashelpedscientists Deep-seaexploration waters was low. theshallow waters around it. acoral reef is greater thanthatof Thebiodiversity of andworms. crabs, sponges, algae, fish, speciesincludingcorals, home to thousandsof canbe acoral reef For example, species thatlive inanarea. B biodiversity Theforest hasahigher thanthewheatfield. field. Onlyafewspecieslive inthewheat andweeds. insects, plants, you seewheat When you walkthrough awheatfield, forest. specieslive inthe Hundreds of andanimals. shrubs, trees, What explains differences inbiodiversity? What explainsdifferences How isbiodiversitymeasured? The Variety ofLife Tell why you thinkithappened. explain whathappenedto thedinosaurs. On thelinesbelow, section io Biodiversity tends to increase thecloseryou move toward deep-sea dark thatbiodiversityScientists once of thought biodiversity isthenumber of The common measure of you seedifferent kindsof When you walkthrough aforest, chapter Read toLearn YouBefore Read di 17 v 3 Also covers: that humans…maydeliberatelyorinadvertentlyaltertheequilibriuminecosystems. student knowsthepositiveandnegativeconsequencesofhumanactiononEarth’ssystems; Benchmarks—SC.D.2.3.1: e r sit y ● eest h ait flifeinanecosystem. of refers to thevariety SC.G.2.3.2; SC.G.2.3.3;SC.H.1.3.4;SC.H.1.3.5;SC.H.1.3.7 1 Conserving Life Biodiversity The studentunderstandsthatthequalityoflifeisrelevanttopersonalexperience; SC.G.2.3.4 AnnuallyAssessed: SC.D.2.3.2 AnnuallyAssessed: that supportthemainidea. paragraph. Thencirclethedetails Underline themainideaineach Identify theMainPoint 1. ■ ■ ■ What You’llLearn ihs biodiversity? highest that havethe climates characteristics of Explain ecosystem biodiversity inan factors thatlimit ecosystem important inan why biodiversityis about biodiversity Reading Essentials The studentunderstands What arethe The 255 ● influences onbiodiversity. identify positiveandnegative Foldable, asshownbelow,to A 2. 256 Identify Define species? Conserving Life Influences Positive Biodiversity What isanextinct Make atwo-tab Influences Negative oltnsbekdw,andclimates are stable. pollutants break down, soilsare richer, biodiversity, As aresult of matter. cycling of Every plays role acertain speciesonEarth inthe clothing. andfiberfor buildingproducts, medicines, food, people with ext An thepassengerpigeonisextinct. however, Today, America. anecosystem. died out?Biodiversity helps keep of thestability theplantspecies What would happen if that ate theherbivore. andonecarnivore species herbivore speciesthatate theplant, one thataforest Imagine hadonlyoneplantspecies, exists. mayfarmers helpprevent a diseasefrom spreading. By alternating rows, anothercrop. and thenext row of grapevines Farmers may plantonerow of thedisease. with canbecome thewholevineyard infected Soon, together. from oneplantto grow thenext becausevines close itcaneasilymove inavineyard, disease infectsagrapevine plant speciesdiscovered could bethecure forcancer. Thenext Scientistsare stilldiscovering newspecies. plants. resists fungaldisease. crossbred corn that of beganusinganewstrain farmers American In the1970s, that are resistant to many diseases. helpsdevelop species plantstrains wild food crops with aroundpopulation all theworld. helpfeedthehuman species Hundreds of healthy. Why isbiodiversityimportant? What changesbiodiversity? tobiodiversity? Why isstabilityimportant Why dohumansneedbiodiversity? changes intheenvironment. canbecome They extinct be from otherspecies. Speciescanbecome ext Earth. that many specieshave become ex has diedout. idvriyi motn o ayraos It provides formanyBiodiversity isimportant reasons. bu 0 er g,passengerpigeonsflewacross North About 100years ago, theforest still plantinaforest disappears, of onetype If a if For example, Biodiversity strengthens anecosystem. Most medicines usedtoday camefrom wild originally Crossbreeding Biodiversity canhelpimprove foodcrops. foodsisagoodway forpeopleto stay of Eating avariety xicini omlpr fntr.Fossil records show nature. of part Extinction isanormal inct sp e cies is aspeciesthatwasonce but present onEarth ntbcueo competition inct becauseof tinct since lifeappeared on cause of

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. ndne fbecoming extinct isan dangerof in to know which speciescould more speciescould belost. increases, As the human population time. of thatsameperiod during tropical becameextinct species Hundreds of 1980 and2000. and animalsintheUnited States becameextinct between plants About 40speciesof extinctions appearsto berising. Therate of many species. contribute to theextinction of probably human activities however, Today, becoming extinct. What are endangered species? endangered What are What causesspeciestodieout? Mass Extinction fmammalsappeared onEarth. of many newspecies After thedinosaursdisappeared, appear. new specieseventually After amassextinction, survive. leading to climate changes thatmany speciescould not fromcaused dustto blocksunlight reaching Earth’s surface The impactmay have intometeorite crashed Earth’s surface. includingdinosaurs. at thattime, onEarth living species all outalmost two-thirds of wiped It occurred intheMesozoic Era. below, on thegraph shown Thatextinction, about65millionyears ago. Earth Oneoccurred on disaster causesmany speciesto dieout. opeetseisfo eoigetnt itisimportant To prevent from species becoming extinct, Humans didnothave thedinosaurs anything to do with This extinction might have extinction might This happenedbecauseahuge Extinction rate (Families of species per million years) 10 15 20 0 5 Mass Extinctions inEarth’sMass Extinctions History A massextinction happenswhen a Ordovician Late 3 6 4 0 50 65 208 245 360 438 Millions ofyears ago Paleozoic Devonian Late ondsper A species soon disappear. Permian- Triassic Triassic Late e ndang Cretaceous- Tertiary Mesozoic e r e d sp e cies . Picture This 3. 4. during theMesozoicEra. extinctions thatoccurred names ofthemass Identify Infer becoming extinct? lead tomorespecies growing humanpopulation Reading Essentials How mighta Circle the 257 Picture This 5. 6. 258 to themap. major citiesofsouthFlorida map ofFlorida,addthe Synthesize Explain biodiversity. ecosystem mightaffect Conserving Life how changingan Using aroad reduced theirpopulationeven more. Thishas hasblocked fromlogging thesunlight theseplants. thepinegrown for Now, already hadalimited range. plant The coast between Tallahassee andPanama City. It canbefoundneartheGulf carnivorous plant. species of small breeding populationexists innationalandstate parks. onlya Now, diseases have greatlyreduced theirnumbers. Pollutants have entered theirfoodchain and the land. theirhabitathas beenlostascitieshave expanded to ﬁll of Much pantherpopulation. led to thedeclineinFlorida Human actionshave onthemapbelow. asshown Florida, southwest Now of are they onlyfoundinasmallpart asTennessee. andasfarnorth asfarwest asLouisiana, Florida, Thisspeciesor species intheworld. in habitatavailable fortheKey Largo cotton mouse. has led toThe increase and people adecrease inbuildings keys The have become destinations. populartourist Keys. Key Largocotton Florida mouse lived thenorthern on all the For example, or extinct. threatened, become endangered, many specieslosetheirhabitats. be reduced if Biodiversity can the forest may become smallerordisappear. many speciesthatlived in thehabitatsof lot, a parking with future are Human Impact What causeshabitatloss? species? threatened What are h oso habitatisamajorreason why many species The lossof such asreplacing aforest When peoplechange anecosystem, thatareSpecies likely to become endangered inthenear Panthers thr Present RangeoftheFloridaPanther e at The Florida pantheristhemostendangeredThe Florida e ne d sp e cies . The Godfrey’s isa butterwort iginally lived of iginally inallparts

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. new strategy limitsbuildinginNorth Keynew strategy Largo’s forests. A didnotsucceed. effort This a newhabitatintheKeys. to introducescientists tried theKey Largocotton mouseto At first, habitatloss. become athreatened speciesbecauseof limit biodiversity. Any change can inplantgrowth habitats formany species. Plants provide plantsorlimittheirgrowth. can harm Soil thatiscontaminated chemicals orotherpollutants with into thearea. No salamanderslive to nearby move never return. might salamanders trees surrounded by paved lots, parking grove of afire destroys a if However, to replace thosethathaddied. theforest thatwasnotdamagedmove in of from thepart salamanders theforest, trees have of grown inthatpart After new are destroyed. inthatpart salamanders living the aforest, fire a destroys of asmallpart If from adisaster. forced to move somewhere else. theanimalsare theirhabitatsare divided, If territories. are aproblem forlargeanimalsthatneedhunting habitats Divided habitat. have habitatusually less biodiversity thanlargeareas of Small areas of orfarms. cities, roads, southern Florida. southern trees The have reduced biodiversity in their foodsource. andanimalsthatate those native specieslost species died, Native Thetrees quicklytook over. theswamps. to “dry up” brought themelaleucatree from They Australia on theland. People wanted to theswampsandbuild drain swampland. organismsinanecosystem. original Pollution ecosystems? speciesaffect How canintroduced biodiversity? How canadividedhabitatreduce Protecting Habitats species cancrowd outnative species. gr this species the populationof so usually have nopredators orcompetitors inthenewarea, Thesespecies human actions. ecosystem asaresult of olto fln,wtr or airalsoaffectsbiodiversity. water, land, Pollution of An Small habitatareas make to itdifficultforspecies recover Biodiversity canbereduced by whenahabitatisdivided In the early 1900s, much of southern Florida was Florida southern much of In theearly1900s, int r o d uc e d sp e cies The Key Largocotton mousehas is aspeciesthatmoves into an w ucl.Introduced ows quickly. N at i v e sp e cies are the SC.D.2.3.2 ✔ 8. FC A T

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U U S S Determine Benchmark Check Annually Assessed Reading Essentials Why does What 259 ● warming andozonedepletion. the Foldabletodescribeglobal Foldable, asshownbelow.Use B 9. 260 Describe Apply organisms? pollution affectaquatic Conserving Life Warming Global How doeswater Make atwo-tab Depletion Ozone ecnaeo CO percentage of Thiscontributes to anincrease inthe fuel. amounts of Humans large burn orany otherfuelisburned. gas, coal, depend onforfood. andtheorganismsthey insects, fish, kill aquaticplants, Thepollutantscan from lawns andfarms. orrunoff ships, pollutantscome These from factories, that live inthewater. called fromradiation reaching Earth’s surface. theSun’s (UV) ultraviolet preventing amountsof damaging Theozone layer protects by lifeonEarth Earth’s surface. It isabout15kmto 30kmabove ozone gas. made upof by airpollution. environmental disasters such as drought orflooding. the trees andmake diseasesor them lessableto survive Thiscanweaken sometrees. damage theleaves orneedlesof Air pollutioncan many organisms. tissuesof can harm fish. makes thewater too acidicformany speciesof Acid rain and otherorganismsthatlive inlakes andstreams. Acid fish alsoharms rain makingthesoillessfertile. soil, It washesaway from calciumandothernutrients the trees. Acid damages rain watercombine vaporintheair. with nitrogen oxide released andautomobiles by industries omr ae fskincancer inhumans. to more casesof canlead UV radiation Increased amountsof Earth’s surface. to organisms reach thatcanharm theUVradiation more of What causeswaterpollution? What isozonedepletion? climate thatcould affectbiodiversity. canleadto changes in warming, global called temperature, in Thisrise may Earth’s raise average temperature. What isglobalwarming? What causesairpollution? Pollutants thatcontaminate thewater organisms harm h zn ae sbcmn hne.Thisthinningis The ozone layer isbecoming thinner. theatmosphere thatis The ozone layer of isthepart dioxideCarbon (CO iscaused water asacidrain pollutionknown of A form i olto rmfcois oe lns andautomobiles power plants, Air pollutionfrom factories, o z o ne d e ple A 2 cid r t nteamshr.An increase inCO in theatmosphere. io n . 2 ain ) isreleased into theairwhenwood, The thinningozone layer allows forms whensulfurdioxideforms and 2

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 3. 2. 1. extinct species: endangered species: biodiversity: acid rain: Mini Glossary what youwhat read aboutbiodiversity? How detailshelp you themainideaandcircling remember supporting didhighlighting Complete by listingthree thatreduce thisdiagram things biodiversity. explains thedifference between introduced speciesandnative species. Write asentence that Review theterms andtheirdefinitionsintheMini Glossary. After You Read has diedout water vaporintheair released byindustriesandautomobilescombinewith eoigextinct becoming results whensulfurdioxideandnitrogenoxide the varietyoflifeinanecosystem species thatwasoncepresentonEarthbut species thatisindangerof games, andprojectstohelpyou learnmoreaboutbiodiversity. Visit fl7.msscience.com Causes to accessyourtextbook,interactive threatened species: ozone depletion: native species: introduced species: as aresultofhumanactions endangered inthenearfuture the originalorganismsinanecosystem the thinningofozonelayer species thatmovesintoanecosystem species thatislikelytobecome Reading Essentials Biodiversity is reduced. Effect Section End of 261 your outline. starting pointfororganizing the headingsinreadingasa learn aboutinthissection.Use outline oftheinformationyou ● Make anOutline f1973. of U.S. EndangeredSpeciesAct conservation biologyandthe the Foldabletodescribe Foldable, asshownbelow.Use C section 262 ■ ■ ■ What You’llLearn chapter Describe Study Coach original habitat reintroduced intoits species canbe how anendangered extinction ofspecies ways topreventthe conservation biology the goalsof 17 3 Also covers: that humans…maydeliberatelyorinadvertentlyaltertheequilibriuminecosystems. student knowsthepositiveandnegativeconsequencesofhumanactiononEarth’ssystems; Benchmarks—SC.D.2.3.1: Conserving Life Conservation Endangered Species Act of 1973 Biology ● 2 SC.H.1.3.3; SC.H.1.3.6;SC.H.3.3.6 Conserving Life Make atwo-tab Conservation Biology Make an The studentunderstandsthatthequalityoflifeisrelevanttopersonalexperience; harm thesespeciesortheirhabitats. harm government from onprojects spending money thatmight Thelaw alsoprevents theU.S. threatened specieslists. any speciesontheendangered or thehabitatof disturb or harass, collect, Thislaw makes itillegalto harm, 1973. Endangered Species Act of One such law istheU.S. habitat. habitats. the species’ protect thespeciesfrom harm. How can laws protect aspecies? How canlawsprotect BiologyatWorkConservation Biodiversity Protecting tell why you thinkzoos exist. On thelinesbelow, conservation planstoconservation satisfyallneeds. itisdifficultto make other speciesare often different, humans and becausetheneedsof However, population. thehuman have thestrategies to consider theneedsof loss, have human Because activities much this to dowith ecology. are of basedontheprinciples Theirstrategies species. a membersof to stop thecontinuingstrategies lossof c o Laws canbepassedto protect boththespeciesand its Onegoalisto Most planshave conservation two goals. methodsforprot The study of nse Read toLearn YouBefore Read r v at io n biolo g y . Conservation biologists develop biologists Conservation SC.G.2.3.4 AnnuallyAssessed: The othergoalisto protect ecting biodiversity iscalled SC.D.2.3.2 AnnuallyAssessed: The studentunderstands The

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. ertr fatleast712km of territory Amalepantherneedsa endangered panther. Florida corridors. wildlife to is solve thislandproblem Oneway to to create largenature preserves. always possible large need areas. wildlife Nature andprotected preserves includenationalparks Oneway isto setupnature preserves. protect habitats. works to biology Conservation its habitatalsoisprotected. 25,000 plantspeciesare protected. Under about5,000animalspeciesand thisagreement tusks. such aselephantivory thespecies, species orany of part speciesbycertain controlling inthese international trade itsgoalsisto protect Oneof (CITES)wassetup. and Flora Wild Fauna on International Trade inEndangered of Species TheConvention In 1975, endangered orthreatened species. What isthepurposeofwildlifecorridors? Protecting theFlordia Everglades habitatsbeingprotected? How are What isCITES? Enforcement from nearextinction. The Act come several species hashelped back in Florida. Environmental Protection enforces thelaw of Department TheFlorida by theUnited States Fishand Wildlife Service. crossing roads orentering areas where humans live. panthers to move from onepreserve to anotherwithout Wildlife allow corridors theprotected pantherhabitats. of freshwater andsaltwater habitats are now protected by law. Its rare mixof tropical andtemperate species. a mixof Visitors to theEverglades National Park canview extinction. someanimalswould becloserto areas, andwildlife parks Without national reasons. setasideforbiological national park It wasthefirst dedicated theEverglades National Park. President STruman Harry In 1947, Everglades. Florida worked conservationists hard to findways to protect the of Wildlife corridors are part of a strategy forsaving the astrategy Wildlife of are corridors part panther, such as the Florida Some large-animalspecies, A speciesthatisprotected by law unless cannotsurvive The United to States othercountries protect works with mut fln osrie oee,itisnot However, landto survive. amounts of h ..Endangered Species Act isenforced The U.S. 2 . This area This islargerthanmany . link smaller parks togetherlink smallerparks with o ayyas agroup For many years, ● and wildlifecorridors. preservation, habitatrestoration, importance ofhabitat Use theFoldabletoidentify tab Foldable,asshownbelow. D 1. Identify corridor? purpose ofawildlife Explain Reading Essentials Preservation Restoration Corridors Wildlife Habitat Habitat What isthe Make athree- 263 Picture This 3. 2. 264 fishing licenses? purpose ofhuntingand Explain Identify habitat restoration. community thatmayneed Conserving Life a placeinyour What isone be restored. becoming too large foranarea. help prevent a po Hunting alsocan rules animalsahunter isallowed. usually limitthenumber of Licenses It alsohelps prevent overhunting. area. wildlife the licenses fortakingcare provides money of The saleof allowed to buy unlessthey hunt alicense. orfishin apark People usuallyare not protect animalspecies. certain are thearea. who studying otherthanbiologists visitors preserves donotallow Somewildlife tusks. their ivory to parks preventwildlife poachers from killingelephantsfor guards patrol inSouth Africa, For example, the areas. People are neededto manage therespecies living from harm. How are habitatsbeingrestored? How are What isthepurposeofwildlifemanagement? enipratt h ucs ftheproject. to thesuccessbeen important of andvolunteers Students have Environmental Protection. of place forbird wildlife. andmarine alsoprovides a Thereef waves andgives oysters ahabitat. which protects aquatic plantsfrom the man-made reef, a formed Thematerials thecoast. in thesaltmarshoff recycled concrete andlimestone rock placed 20,000tons of Workers and saltmarshto thePensacola Bay ecosystem. Its goalisto returnanoyster reef habitat restoration effort. adamagedhabitatbacktoaction to ahealthy bring condition. Habitats thathave by beenharmed can human activities Wildlife managersandhunters often work together to Wildlife andpreserves parks donotautomatically protect Project Greenshores Department ismanagedby theFlorida beganin2001asa shown below, Project Greenshores, H abitat r est o r at Cheryl Bunch/ProjectGreenshores/FloridaDept.ofEnvironmentalProtection io n stepoeso taking is theprocess of pulation from

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. How can keeping animals in captivity preserve biodiversity? Sometimes endangered or threatened animals are placed in zoos. Often these animals are no longer found in the wild. A captive population is a population of organisms 4. List one advantage and one disadvantage of that is cared for by humans. Often, with human care, the captive population? numbers of the species increase. Keeping endangered or threatened animals in captivity can help preserve biodiversity. However, it is not an ideal solution. Providing food, space, and care can be expensive. Sometimes captive animals lose their wild behaviors. If that happens, these animals might not survive if they are returned to their habitats. What is the purpose of reintroduction programs? Sometimes members of captive populations can be put back into the wild to help restore biodiversity. Reintroduction programs return captive organisms to an area where the species once lived. Once reintroduced, researchers may observe the animals from a distance. These programs can be successful only if the reasons that caused the species to become endangered are removed. Plants also can be reintroduced into their original habitats. Often this is done by replanting seedlings in the original habitats. How are seed banks used? Seed banks store the seeds of many endangered plants species. There are seed banks throughout the world. If a species becomes extinct in the wild, the stored seeds can be planted to reintroduce the plants to their original habitats. Why are some species relocated? Reintroduction programs do not always involve captive populations. The most successful reintroduction programs happen when wild organisms are moved to a suitable new 5. Analyze Why might habitat. The brown pelican relocation is an example of this. reintroduction programs be more successful with wild The pelican was once common along the Gulf of Mexico. species than with captive In the mid-1900s, a pesticide known as DDT ended up in the species? food that pelicans ate. Because of DDT, the pelican’s eggshells became so thin that they broke before the chicks could hatch.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Soon, pelicans disappeared from Louisiana and most of Texas. In 1971, pelicans were reintroduced to the area. By the year 2000, more than 7,000 brown pelicans lived in Louisiana and Texas. The United States banned the use of DDT in 1972.

Reading Essentials 265 2. 1. conservation biology: captive population: Mini Glossary 266 Use below to usedto theweb diagram identifydifferent protect strategies biodiversity. asentence explaining isbeingdonetowrite what protect biodiversity. theterms, Using two of Review theterms andtheirdeﬁnitionsintheMini Glossary. After You Read Section cared forbyhumans biodiversity End of Conserving Life a populationoforganismsthatis the studyofmethodsforprotecting Ways toProtect Biodiversity biology. games, andprojectstohelpyou learnmoreaboutconservation Visit reintroduction program: habitat restoration: ﬂ7.msscience.com organisms toanareawherethespeciesoncelived damaged habitatbacktoahealthycondition the processoftakingactiontobringa to accessyourtextbook,interactive a programthatreturnscaptive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chapter Our Impact on Land 183 section ●1 Population Impact on the Environment Benchmarks—SC.D.2.3.2 Annually Assessed: The student knows the positive and negative consequences of human action on the Earth’s systems. Also covers: SC.D.2.3.1; SC.G.2.3.4; SC.H.1.3.3; SC.H.1.3.6

Before You Read What You’ll Learn ■ how fast the human How do you think the total number of people on Earth in population is increasing 1900 compares to the human population in 2000? How will ■ why the human the population change in the next 100 years? population is increasing rapidly ■ ways you can affect the environment

Read to Learn Study Coach Create a Quiz As you read Population and Carrying Capacity the text, write a quiz question for each topic. When you have Humans share Earth with many other living things. Look ﬁnished reading, try to answer around and you might see ﬁsh in a tank, squirrels in a tree, your questions correctly. or plants in the yard. These are examples of populations. A population is the total number of individuals of one species occupying the same area. That area can be large or small. A human population can be of one community, such as Tampa, or the entire planet. Is Earth’s population increasing? In 2000, there were 6.1 billion humans on Earth. Each day, approximately 200,000 more humans are born. Earth is experiencing a population explosion. The word explosion is used because the rate at which the population is growing is rapidly increasing.

How much has the human population grown? ●A Think Critically Make Many years ago, few people lived on Earth. Look at the the following three-tab Foldable graph of population growth on the next page. It took to explain the three factors that Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright thousands of years for the population to reach 1 billion affect the world’s population. humans. After the mid-1800s, the population grew much faster. This type of growth is called exponential. The growth rate multiplies as the population increases.

Reading Essentials 267 Applying Math Population Growth of Modern Humans 10 1. Use Graphs What was 9.1 billion the approximate human 9 2050 population in 1950? 8 7 6.1 billion a. 2 billion 2000 b. 2.2 billion 6 c. 2.8 billion 5 d. 3.1 billion 4 3 billion 3 1960 2 1 billion 600 million 1810

Human population (billions) 1 1700 0 100,000 1700 A.D. 1800 A.D. 1900 A.D. 2000 A.D. 2100 A.D. (years ago) Year

Why has the human population grown? The human population has increased because modern medicine, clean water, and better nutrition have decreased the death rate. This means that more people are living longer. Also, more babies are being born because more people reach the age at which they can reproduce. By 2050, the population is predicted to be about 9 billion, or one and a half times what it is now. What effect will this population increase have on the environment? Will Earth have enough natural resources to support such a large population? What will become of the things that have helped the population grow, such as health care and clean water? What are population limits? Each person uses space and resources. Population size depends on the amount of resources that are available. It also depends on how members of a population use their resources. For example, if an area has a long drought, the amount of freshwater resources will decrease. If members of a population pollute their drinking water reservoirs, the result is the same. The population will suffer and the F T OC A U C Annually Assessed population size could decrease.

S F Benchmark Check Humans once thought that Earth had an endless supply of SC.D.2.3.2 natural resources, such as fossil fuels, clean water, rich soils, and metals. It’s now known that Earth’s resources are limited. ✔ 2. Deﬁne What is carrying capacity? The planet has a carrying capacity. Carrying capacity is the Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright largest number of individuals of a particular species that the environment can support. If people waste or pollute Earth’s resources, they could disappear, and the human population could reach its carrying capacity.

268 Our Impact on Land Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. oil canproduce pollutants. reﬁning Theprocess of Plasticismadefrom oil. and paper. things. living itcanthreaten thehealthof great, chemicals istoo theconcentration of If water supplies. Thesechemicals cangetinto toand herbicides killweeds. such aspesticidesto killinsects using chemical substances, Many vegetables are grown which needssoilto grow. food, You eat possible before beingreturned to theenvironment. thesesteps changes theenvironment. Each of energy. Fossil to fuelsmust beminedandthen burned create often comes from forelectricity fossilfuels. The energy elsewhere intheworld. uses many timesmore resources thanapersonliving intheUnited living Aperson States ﬁll 68,000bathtubs. That’s water to enough water. consumed liters 18million of You have will 11 elephants. African equal to themassof Thatis garbage. you have will produced 53,000kgof old, by thetimeyou’re 75years you are like most Americans, If What are pollutants? What are environment? the How dodailyactivitiesaffect People andtheEnvironment environment. you canlessentheimpact onthe conserve resources, you If and products thatcome from resources. natural Humans must thinkcarefully before resources using natural more resources beusedandmore becreated. waste will will As thepopulationincreases, items create additionalwaste. Unnecessary anddisposable packaging away asgarbage. process. inthepapermaking Water andairpollutantsare given off Trucks trees to mill. thepaper useoilto transport down. Trees are cut making papercandamagetheenvironment. thesteps usedin Several of contaminate theenvironment. ayo h rdcshmn s r aeo plastic theproducts humans useare madeof Many of Water thatisusedmust betreated to make itasclean theenvironment isaffected by human activity. Every day, How you will affecttheenvironment over your lifetime? After many products are made and used, they are they thrown After many products are madeand used, P ol l u tants are substances that ● the environment. daily activitiesaffectlandand to helpyouunderstandhow following three-columnFoldable and Effect B 3. Understand Cause vegetables? used whengrowing pesticides andherbicides Identify

Activities

Daily Reading Essentials Resources Make the Used

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Produced Waste 269 3. 2. 1. pollutant: carrying capacity: Mini Glossary 270 information inthis section? information to findanswers to your questions?Didthequestionsyou wrote helpyou understandthe What resources could you use Review thequestionsyou wrote asyou read thissection. Complete theconcept mapto show you understandEarth’s capacity. carrying theenvironment. theterms to show how humans canorshouldtake care of using oneof asentence Thenwrite above. Review theterms andtheirdefinitionsintheMini Glossary After You Read Section given speciesthattheenvironmentcansupport End of Our ImpactonLand substance thatcontaminatestheenvironment are nottakencareof. ______Earth’s the largestnumberofindividualsa that Earthwillsupport. ______of individualsagiven the maximumnumber resources areused. toomany grows, and a ______Carrying Capacity It maybereachedif is impact ontheenvironment. games, andprojectstohelpyou learnmoreaboutpopulation Visit population: fl7.msscience.com occupying thesamearea total numberofindividualsonespecies population. left tosupporta ______there isnotenough to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. h muto foodgrown oneach km the amountof to Farmers usechemical increase fertilizers to beproduced. more foodneeds To feedagrowing population, for farming. All of these activities canaffectEarth’s theseactivities landresources. All of garbage. It isusedto buildcitiesandto disposeof products. Landisusedto grow forest foodandharvest water. Yet to humans ascleanairandfresh itisasimportant ,0 years fornewtopsoil to develop. 1,000 ittakes more than In someplaces, be lostinoneyear. topsoilmay of Several centimeters waterrunning andwind. thesoilcanbecarried away by roots to holdsoil inplace, thehumans onEarth. feed allof cannotcurrently produce farming organic foodto enough However, methods helpcrops grow usingchemicals. without These controls. pest andbiological crop rotation, fertilizers, other peststhatcandamagecrops. and insects, areand pesticides alsoused to reduce weeds, theland? affect How doesagriculture Land Usage theenvironment. harm landmight useof particular how Describe this oneway thathumans useland. Think of section About 16 millionkm resource. landasanatural Many peopledonotthinkof hnfrln stle,si sepsd Without plant soil isexposed. When istilled, farmland natural techniquesOrganic farming includetheuseof chapter Read toLearn YouBefore Read 18 3 Also covers: Benchmarks—SC.D.2.3.1: ● 2 SC.D.2.3.2; SC.D.1.3.4;SC.G.2.3.4;SC.H.1.3.4;SC.H.3.3.1;SC.H.3.3.4 Our ImpactonLand Using Land The studentunderstandsthatthequalityoflifeisrelevanttopersonalexperience. 2 fEarth’s total landsurface isused of 2 fln.Herbicides land. of be preserved. ways landisusedandhowitcan organize informationabout sheet Foldablestohelpyou ● with otherstudents. questions aspartofadiscussion you haveaquestion.Usethese mark pagesinthetextwhere As youread,usesticky-notesto Sticky-Note Discussion Information C What You’llLearn ■ ■ ■ Organizing Study Coach Lumber environment help protectthe things youcandoto problems environmental how landusecreates ways thatlandisused Farming Reading Essentials Development Make quarter- Grazing Disposal 271 How can soil erosion be reduced? Some farmers till, or turn over, the soil before planting a new crop. However, other farmers practice no-till farming. They don’t plow the soil from harvest until planting. Instead of tilling, they simply plant seeds between the stubble of last year’s vegetation. Another method of reducing soil loss is contour plowing. Rows are tilled across hills and valleys. When it rains, water and soil are trapped in the plowed rows, reducing soil erosion. Other techniques include planting trees in rows along ﬁelds. The trees slow the wind, reducing the amount of soil that can be blown away. Cover crops—crops that are not harvested—also can be planted to reduce erosion. 1. Summarize What is one How is land used to feed livestock? method used in farming to reduce soil loss? Land also is used for feeding livestock. Animals such as cattle eat the vegetation growing on the land. Then the animals are used as food for humans. Many farmers grow corn and hay just for feeding their livestock. These crops provide cattle with a variety of nutrients and can improve the quality of the meat. What are forest resources? According to the Food and Agriculture Organization of the United Nations, about one-fourth of the land on Earth is covered by forest. About 55 percent of this forest is found in developing countries. The other 45 percent occurs in developed countries. Deforestation is the clearing of forested land for agriculture, grazing, development, or logging. It is estimated that the amount of forested land in the world decreased by 0.24% (94,000 km2) each year between 1990 and 2000. Most of this deforestation occurred in tropical regions. How does deforestation affect the environment? Many plants and animals that live in tropical rain forests cannot survive in other places. If their homes are destroyed, 2. Explain How can the they may become extinct. Many of these plants might be cutting of trees affect an area’s climate? important for developing new medicines. Cutting trees can affect climate as well. Water from tree

leaves evaporates into the atmosphere where it can condense Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright to form rain. If many trees are cut down, less water enters the atmosphere and that region receives less rainfall. This is one way humans can affect the water cycle.

272 Our Impact on Land How does development affect land? Between 1990 and 2000, the number of kilometers of roadways in the United States increased by more than 3. Think Critically Why 13 percent. Building highways often leads to more paving as do you think that building a office buildings, stores, and parking lots are constructed. highway in an area leads to Paving land prevents water from soaking into the soil. more construction in that Instead, it runs into sewers and streams. Streams are forced area? to move a larger volume of water. Stream discharge is the volume of water flowing past a certain point per unit of time. If enough rainwater flows into streams, it increases stream discharge. Then streams may flood. Many communities get their drinking water from underground sources. When land is covered with roads, sidewalks, and parking lots, less rainwater soaks into the ground to refill underground water supplies. Some communities and businesses have begun to preserve areas rather than pave them. Land is being set aside for environmental protection. What are sanitary landfills? Land also is used to dispose of garbage. About 60 percent of our trash is put into sanitary landfills like the one illustrated below. A sanitary landfill is an area where each day’s garbage is deposited and covered. Covering the garbage keeps it from blowing away. It also reduces the odor that comes from decaying waste. The figure below shows how sanitary landfills are designed to prevent liquid wastes from seeping into the soil and groundwater below. New sanitary landfills are lined with plastic, concrete, or clay-rich soils that trap the liquid waste. These linings greatly reduce the chance that pollutants will soak into the surrounding soil and groundwater.

Pipes for venting gas Soil Garbage Picture This 4. Identify Highlight the part of the landﬁll that prevents liquid waste from polluting the soil and groundwater. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Gravel/Rock Cement, clay, Fluid-collection layer or plastic liner system

Reading Essentials 273 5. 6. 274 Define is difficult. new placetobuildalandfill List phytoremediation? Our ImpactonLand reasons whyfindinga What is considered. concerns andneighborhood must be depth to groundwater, the soil, Type of area to buildalandfillcanbedifficult. Locatinganacceptable newonesmust bebuilt. garbage, When landfillsare filledwith decompose slowly. very edsoe fatasite. be disposedof the ashesleftbehindstill contain hazardous waste andmust theseplantsare destroyed by burning, If metals orburned. must beharvested and eithercomposted to recycle the areas to remove metalsfrom theharmful thesoil. People cangrow theseplantsinpolluted other nutrients. metalsfromharmful contaminated canabsorb absorb soilsjustasthey andpinetrees, grasses, such asalfalfa, plants, remediation (FI toh meedee ruh AY shun). cleaning polluted phytoremediation soiliscalled Onemethodfor canpollute soiland water. industries government to findoutaboutcollection sites inyour area. Contact your local special hazardous waste-collection sites. hazardous wastes at You canhelpby disposingof to decay. years Thesesubstances take hundreds and of paints inthetrash. medicines, bleaches, cleaners, drain batteries, sprays, catch fire are called or can causecancer, Wastes thatare poisonous, organisms. How dolandfillsuseupalandresource? What isphytoremediation? disposed ofproperly? wastesbe How canhouseholdhazardous WastesHazardous hr sls edt ips fthem. there islessneedto disposeof Now have since developed to helprecycle hazardous wastes. New technologies hazardous landfills. wastes into sanitary newlaws to put madeitillegalforindustries In the1980s, once were regular householdgarbage. putinlandfillswith Many donotdecompose materials inlandfillsor lnsta bobtomc fthesemetalseventually too muchPlants thatabsorb of Hazardous substances from leakinglandfillsornearby Most throw individuals hazardous such materials asinsect thewastes thrown away are dangerous to Some of en t xapolm”Teroso certain roots The of means “to fixaproblem.” hazar d ous wast Phyto es . en pat and means “plant” Hazardous wastes

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. some land in its natural state will benefitfuture state generations. some landinitsnatural will Preserving ontheenvironment thestrain may worsen. grow, As theworld populationcontinues to preserves. natural Many alsosetasidelandfor othercountries preserves. thatare and usedfornationalparks thecountry areas of Themapbelow shows some protected from development. intheUnited andnational parks States are grasslands, National forestlands, mostly uninhabited by humans. Somelandremains produce somethinghumans canuse. An (ENzimez)into thesoil. enzymes plantroots Some release substances to asnutrients grow. theseharmless Plantsusesomeof substances. harmless organiccompounds. made of are such asgasolineandoil, Somepollutants, compounds. are calledorganic andnitrogen, oxygen, hydrogen, such as Substances thatcontain andotherelements, carbon ucl.Thenthe plant canusethesesubstances forgrowth. quickly. plants release causeorganicpollutantsto break more down these enzymes The that makes achemical reaction gofaster. Natural Preserves down? pollutantsbroken organic How are Not isbeingusedto store alllandonEarth waste or These organicpollutantscanbebroken into down simpler, cancleanuppollutantsotherthanmetals. things Living Valley Death N.P. Lassen VolcanicN.P. Lake N.P. Crater Yosemite N.P. Olympic N.P. Kings Canyon/SequoiaN.P. Mount RainierN.P. Joshua TreeN.P. Grand CanyonN.P. Saguaro N.P. Glacier N.P. Canyonlands N.P. Yellowstone N.P. Carlsbad CavernsN.P. Rocky MountainN.P. Big BendN.P. Badlands N.P. Mammoth CaveN.P. Shenandoah N.P. e nzy Isle RoyaleN.P. Everglades N.P. me Acadia N.P. is asubstance Mountains N.P. Great Smoky Picture This 7. 8. in Florida. Natural Preservefound List Identify organic compound? contain tobeconsideredan elements asubstancemust Reading Essentials What aresomeofthe Circle the 275 3. 2. 1. hazardous waste: enzyme: Mini Glossary 276 questions with otherstudentshelpyou presented? understand thematerial questions with How diddiscussingyour you marked pageswhere you hadquestions. As you read, soilcanhave onland. effects pollutantsandoveruse of the Complete to show cause-and-effect chart thefollowing thatyou understandsomeof theterms to explain how humans affecttheenvironment. using oneof asentence Thenwrite above. Review theterms andtheirdefinitionsintheMini Glossary After You Read Section or cancatchfire End of Our ImpactonLand substance thatmakesachemicalreactiongofaster improperly thrownaway. Hazardous wastesare Sanitary landfillsleak. dug upforconstruction Crops harvestedorvegetation Farmers tillsoil. AS RATO POSSIBLEEFFECT CAUSE ORACTION wastes thatarepoisonous,causecancer, resources. games, andprojectstohelpyou learnmoreaboutland Visit stream discharge: sanitary landfill: fl7.msscience.com point perunitoftime covered area wheregarbageisdepositedand volume ofwaterflowingpastacertain to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. into rags forusearoundinto your rags home. clothescanbegiven Old away orcut throwing itaway. of Reusing anitem meansfindinganother way to useitinstead materials. nondisposable container helpreduce theuseof your lunch to school ina notebook andcarrying paper Using bothsidesof conserve resources insimpleways. You canhelp throwing themaway. insteadmaterials of peoplereuse andrecycle Resources canalsobeconserved if people usefewer intheireveryday disposablematerials lives. Resources canbeconserved if resources thanotherregions. usemore natural such astheUnited States, countries, such metals. ascertain materials, cankeepConservation humans from outof running tomaterials reduce damageto theenvironment. be damaged. theenvironment can these resources are notusedcarefully, If Petroleum isusedto produce plasticsandfuel. bikes. are Minerals usedto make carsand everyday products. Reduce, Reuse,Recycle Use Resource why not? What you might doto helpconserve resources? Do you thinkhumans needto conserve resources? Why or section The graph onthenext pageshowsThe graph thatdeveloped Earth’s resources natural formaking are important chapter Read toLearn YouBefore Read 18 3 Benchmarks—SC.D.2.3.1: Also covers: ● 3 SC.D.2.3.2; SC.G.2.3.4;SC.H.1.3.1;SC.H.1.3.4;SC.H.1.3.6,SC.H.3.3.1;SC.H.3.3.4 C Our ImpactonLand o nse Conserving Resources r v The studentunderstandsthatthequalityoflifeisrelevanttopersonalexperience. at io n stecrflueo Earth is thecareful useof the informationinthissection. you organizeandunderstand words anddefinitionstohelp highlight thenewvocabulary ● Highlight you canconserveresources. to helpyouunderstandways the followingthree-tabFoldable D ■ ■ What You’llLearn Find MainIdeas recycling the advantagesof resources three waystoconserve Reading Essentials Recycle As youread, Reduce Reuse Make 277 2. 1. 278 recyclable materials. world? used intherestof States eachyearthanare are usedintheUnited more litersofoilperperson Identify Use Graphs Applying Math Our ImpactonLand Name some How many into landfillsby 20percent. itwould reduce put thetrash the United States composted, in everyone If foragardenprovide nutrients orflowerbed. Decomposed can material candecomposethey gradually. composted. thosewastes canbe Instead, bagged andthrown away. eue h muto raw taken materials from Earth. reduces theamount of andrecycling useand alsoreduces energy reusing, reducing, In additionto saving landfillspace, decreased since 1980. put inlandfillshas garbage Theamount of sent to landfills. make newproducts. such materials assteel Somebusinesses usescrap to waste. by spendonmaterials recycling they themoney the some of somecompanies canmake back For example, for business. week newspapers. justto print More than500,000trees are cutevery include newspapers. doesnoteven Thegraph producing newpaperfrom trees. less water andgenerate 74percent lessairpollutionthan Recycling thispaperwould use58percent papereach year. of throw Americans away huge amounts abovethe graph shows, andlandfill space. energy, Recycling helpsconserve Earth’s resources, andtires. steel, plastic, paper, recyclable wastes are glass, Examples of object. What materialscanberecycled? wastebereused? How canyard R thewaste isoften When leaves iscut, are raked orgrass hs rcie aemnyadrdc h muto waste These practices save andreduce money theamount of Many businesses have foundthatrecycling canbegood As trash. themassof Paper makes upabout40percent of e cy c ling C 3,800 is processing waste to materials make anew o mp 700 Yearly ConsumptionperPerson ost (L) Oil 340 ing 151 means pilingyard wastes where Steel (kg) 31 5 U.S. Metals (kg) 328 Rest ofworld Paper (kg) 181

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. you canmake adifference. and recycling way that isanimportant reusing, reducing, resources Conserving by resources must beusedwisely. To make upforthis, stop growing inthenearfuture. recycled often becausethey cost isnothigh materials more. thedemandfor However, from recycled must materials exist. Ademandforproducts made inthepictureshown below. as thenmustThe materials beseparated atspecialfacilities, are neededtotrucks separately from haulmaterials trash. container forrecycling. but you backwhenyou cangetthatmoney return the You may whenyou pay forthedrink buy alittleextra it, containers. arefundable drink depositismadeonall places, In other people whorecycle pay lower collection fees. trash What istheoutlookforhuman population? coststorecycling? there Are inuse? are What kindsofprograms It isnot likely declineor thatthehuman populationwill More and people There are disadvantages to recycling. In someplaces, Many states orcitieshave recycling laws. Picture This 3. 4. expensive? materials oftenaremore Why doyouthinkrecycled Draw Conclusions Explain are doinginthepicture. Reading Essentials what theworkers 279 3. 2. 1. composting: Mini Glossary 280 o hn hshle o eebrtedfiiin ftheterms? Why orwhy not? you you thinkthishelped remember thedefinitionsof Do words you thevocabulary andtheirdefinitions. highlighted As you read thesection, recycling. Complete below thechart by listingsomebenefitsanddisadvantages of terms inasentence explaining itsrole fortheenvironment. incaring the Thenuseoneof above. Review theterms andtheirdefinitionsintheMini Glossary After You Read Section eue rs nlnfil Must becarriedseparatelyfromtrash Reduces trashinlandfills decompose gradually End of Our ImpactonLand piling yardwastesinanareasotheycan EEISO EYLN DISADVANTAGESOFRECYCLING BENEFITS OFRECYCLING Visit osrigresources. conserving games, andprojectstohelpyou learnmoreabout recycling: conservation: fl7.msscience.com damage totheenvironment processing wastematerialstomakeanewobject careful useofEarthmaterialstoreduce to accessyourtextbook,interactive

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. chapter Our Impact on Water and Air 193 section ●1 Water Pollution Benchmarks—SC.D.2.3.1: The student understands that the quality of life is relevant to personal experience. Also covers: SC.D.2.3.2; SC.G.2.3.2; SC.G.2.3.4; SC.H.1.3.5; SC.H.1.3.6; SC.H.2.3.1; SC.H.3.3.1; SC.H.3.3.4

Before You Read What You’ll Learn ■ types of water On the lines below, list some of the ways you use water. pollutants and their effects ■ ways to reduce water pollution

Read to Learn Highlight Main Ideas As Importance of Clean Water you read the text, highlight the main idea in each paragraph. All organisms need water. Plants need water to make food using sunlight. Some animals, such as fish and whales, live in water. Humans and other land animals cannot live without drinking water. What happens if water isn’t clean? Polluted water contains chemicals and organisms that can cause disease and death in many living things. Water also can be polluted with sediments, such as silt and clay. Sources of Water Pollution Imagine you are hiking near a stream or lake. If you become thirsty, would it be safe to drink the water? Many streams and lakes in the United States are polluted in some way. Even streams that look clear and sparkling may not be safe for drinking. ●A Compare and Contrast Point source pollution is pollution that enters water from Make a four-tab Foldable to a specific location, such as drainpipes. Pollution from point record information about water sources can be controlled or treated before the water flows pollution. into a body of water. Often, no one knows exactly where water pollution comes

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright from. Nonpoint source pollution enters a body of water from a large area, such as lawns, construction sites, and roads. Nonpoint sources also include pollutants in rain or snow. Nonpoint source pollution is the largest source of water-quality problems in the United States.

Reading Essentials 281 How does sediment pollute water? The largest source of water pollution in the United States ●B Cause and Effect Make is sediment. Sediment is pieces of rock and loose soil that a chart Foldable, as shown below, to show the causes and are moved by erosion. Although rivers always have carried effects of water pollution. sediment to oceans, human activities have increased the amount of sediment flowing into rivers, lakes, and oceans. Each year, about 25 billion metric tons of sediment are carried from farm fields to bodies of water. At least 50 billion more tons run off of construction sites, cleared forests, and land used to graze livestock. Sediment makes water cloudy, blocking the sunlight that underwater plants need to make food. Sediment covers the eggs of organisms that live in the water, preventing them from getting the oxygen they need to develop. How do farm and lawn chemicals pollute water? Pesticides are substances that kill pests. Farmers and homeowners use pesticides to kill insects and plants that harm their crops and lawns. Some of these chemicals run off the land and into water, where they may be harmful to people and other organisms. Fertilizers are chemicals that help plants grow. However, rain washes away as much as 25 percent of the fertilizers applied to farms and yards. This fertilizer ends up in ponds, streams, and rivers. Fertilizers contain nitrogen and phosphorus. The algae living in the water use these chemicals to grow and multiply. A lake or pond, such as the one in the figure below, can become choked with algae. When the algae die and decay, oxygen in the lake is used up, and fish and other organisms in the water may die.

Picture This 1. Summarize Use the information in the ﬁgure to help explain how fertilizers can cause water pollution. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Fertilizer applied to lawns or farms runs off.

282 Our Impact on Water and Air What is sewage? When you ﬂush a toilet or take a shower, the water goes down a drain. Sewage is the wastewater that contains human waste, household detergents, and soaps. Human waste contains harmful organisms that can make people sick. In most cities, sewage treatment facilities purify sewage before it enters a body of water. Can metals cause water pollution? Many metals, such as mercury, lead, and nickel, can be poisonous. Lead and mercury in drinking water can harm the nervous system. Yet these metals are part of many useful items, such as paints, stereos, and batteries. Today, environmental laws control the amounts of metals released with wastewater from factories. Because metals remain in the environment for a long time, metals released many years ago still are polluting bodies of water today. Mining also releases metals into water. For example, in the state of Tennessee, more than 43 percent of all streams 2. Describe two ways that and lakes contain metal from mining activities. metals enter bodies of How do oil and gasoline pollute water? water. When it rains, oil and gasoline run off roads and parking lots into streams and rivers. These compounds contain pollutants that might cause cancer. Gas stations store gasoline in tanks below the ground. If the tanks rust, they can leak gasoline into nearby soil and groundwater. As little as one gallon of gasoline can make an entire city’s water supply unsafe for drinking. Federal laws passed in 1988 require all new gasoline storage tanks to have a double layer of steel or ﬁberglass. In addition, all new and old tanks must have equipment to detect spills and must be made of material that will not develop holes. These laws help protect soil and groundwater. How does heat pollute water? When a factory makes a product, heat often is released. Sometimes, water from a nearby river or lake is used to cool factory machines. Then, the heated water is released back 3. Identify How can into the river or lake. Pollution occurs because hot water factories cool hot water

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright contains less oxygen than cool water. Also, organisms that before releasing it into live in water are sensitive to temperature changes. A sudden rivers? release of hot water can quickly kill many ﬁsh. Water should be cooled in a cooling tower or pond before being released into a river.

Reading Essentials 283 Reducing Water Pollution One way to reduce water pollution is to treat water before it enters a stream or lake. In 1972, the U.S. Congress passed the Water Pollution Control Act. This law provided funds to build sewage treatment facilities and required industries to treat polluted water before releasing it. The Clean Water Act of 1987 set goals for reducing point source and nonpoint source pollution. The Safe Drinking Water Act of 1996 strengthens health standards for drinking water. 4. Explain What goals were How can countries work together? set by the Clean Water Act? Sometimes countries work together to reduce water pollution. Coral reefs are an important part of the ecosystem. They are the home of many different organisms. Unfortunately, they are being damaged by water pollution. In 1998, the United States and many other countries formed a group to help protect coral reefs around the world. How can you help? The quality of many streams, lakes and rivers has improved. However, there is still much work to be done. You can help by disposing of wastes safely and by conserving water. How can wastes be disposed of safely? When you dispose of household chemicals such as paint or motor oil, don’t pour them onto the ground or down the drain. These wastes can move into groundwater or rivers. Instead, read the label on the container for instructions on how to safely dispose of these wastes. How can water be conserved? You use water every time you flush a toilet, take a bath, or wash dishes. Each person in the United States uses an 5. Apply What are two other ways you can average of 375 L of water per day. Unless it comes from a help save water? home well, this water must be purified before it reaches your home. After you use the water, it must be treated again. Some simple ways to conserve water are to turn off water while brushing your teeth, replace an old toilet with a Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright new one, and to fix leaky faucets.

284 Our Impact on Water and Air After You Read Mini Glossary fertilizer: chemical that helps plants grow point source pollution: pollution that enters water from a nonpoint source pollution: pollution that enters water speciﬁc location and can be controlled or treated before from a large area and cannot be traced to a single location it enters a body of water pesticide: substance used to keep insects and weeds from sewage: wastewater that goes into drains and contains destroying crops and lawns human waste, household detergents, and soaps

1. Review the terms and their deﬁnitions in the Mini Glossary. Choose one term and use it to write a sentence telling how water pollution harms people or the environment.

2. Complete the concept map to show the sources of water pollution.

Sediment ______

Water Pollution ______

Fertilizers Oil and gasoline

______

3. As you read this section, you highlighted the main ideas in each paragraph. How did highlighting the main ideas help you understand the information in this section? Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Visit ﬂ7.msscience.com to access your textbook, interactive End of games, and projects to help you learn more about water Section pollution. Reading Essentials 285 chapter Our Impact on Water and Air 193 section ●2 Air Pollution Benchmarks—SC.D.2.3.1: The student understands that the quality of life is relevant to personal experience. Also covers: SC.D.2.3.2; SC.G.2.3.2; SC.G.2.3.4; SC.H.1.3.3; SC.H.1.3.4; SC.H.1.3.5; SC.H.1.3.6; SC.H.1.3.7; SC.H.3.3.1; SC.H.3.3.4

What You’ll Learn Before You Read ■ sources of air pollution ■ types of air pollutants Air is just as important to most life on Earth as water is. and their effects What are some ways air pollution can harm your health? ■ ways to reduce air pollution

Study Coach Read to Learn Create-a-Quiz As you read this section, create a quiz Causes of Air Pollution question for each subject. When you have finished reading, see if Cities can be exciting places. They are centers of business, you can answer your own culture, and entertainment. However, cities also have many questions correctly. cars, buses, and trucks that burn fuel for energy. The brown haze you sometimes see over a city forms from the exhaust of these vehicles. Air pollution also comes from burning fuel in factories, generating electricity, and burning trash. Dust from plowed fields, construction sites, and mines also contributes to air pollution. Natural sources may cause air pollution, too. For example, radon is a gas given off by certain kinds of rock. This gas can seep into basements of homes built on these rocks. Breathing radon can increase the risk of lung cancer. Particles and gases from fires and erupting volcanoes also are natural sources of pollution. ●C Organize Information Make the following layered- book Foldable to organize What is smog? information about air pollution. One type of air pollution found in and around cities is

called smog. Cars, trucks, and motorcycles are the main Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright sources of smog in the United States. Other major sources of smog include factories and power plants. A combination of pollutants and natural conditions leads to the formation of smog.

286 Our Impact on Water and Air How does smog form? Photochemical smog is a hazy blanket of smog that forms with the help of sunlight. When gasoline is burned, nitrogen and carbon compounds are released and pollute the air. The ﬁgure below shows how these compounds produce smog and ozone. Ozone high in the atmosphere protects you from the Sun’s radiation. However, ozone near Earth’s surface is a major component of smog. It can damage your lungs and harm plants.

Smog

D Ozone and other compounds B In the presence of form smog. Picture This sunlight, nitrogen compounds 1. Identify What is the release oxygen atoms. source of the oxygen atoms C Oxygen molecules (O2) that combine with oxygen A Car exhaust in air combine with oxygen molecules in air to form contains nitrogen and atoms to form ozone (O3). ozone? carbon compounds.

How does nature contribute to smog? Landforms may help smog form. Mountains can prevent smog from being carried away by winds. The atmosphere also can inﬂuence smog formation. Normally, warm air near the ground rises into higher layers of the atmosphere. Sometimes warm air traps cool air near the ground. This causes pollutants to accumulate near Earth’s surface. Acid Rain Acids form when sulfur oxides from coal-burning power plants and nitrogen oxides from cars combine with moisture in the air. Acid rain occurs when acidic moisture falls to Earth as rain or snow. The pH scale measures how much acid a substance

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright contains. A pH of 7 is neutral. Acids are substances with a pH below 7. Bases are substances with a pH above 7. Natural lakes and streams have a pH between 6 and 8. 2. Deﬁne What is the pH of acid rain? Acid rain has a pH below 5.6. Acid rain may decrease the pH of streams and lakes, harming some organisms.

Reading Essentials 287 CFCs About 20 km above Earth’s surface is a layer of atmosphere called the ozone layer. Recall that ozone is a molecule made of three oxygen atoms. Ozone in smog near the ground is harmful. However, ozone in the ozone layer helps life on Earth by absorbing some of the Sun’s harmful ultraviolet (UV) rays. Chloroﬂuorocarbons (CFCs) from air conditioners and refrigerators might be destroying the ozone layer. Each CFC molecule can destroy thousands of ozone molecules. Even though use of CFCs has decreased, CFCs can remain in the upper atmosphere for many decades. Air Pollution and Your Health Have you ever had to stay indoors because of an air or smog pollution alert? When smog levels are high, it is not safe to run, bike, or exercise outdoors. Some schools schedule football games for Saturday afternoons when the smog levels are lower. How does dirty air affect health? About 250,000 people in the United States suffer from breathing disorders caused by air pollution. It also causes 3. Identify What is one about 70,000 deaths each year. Ozone damages lung tissue disease caused by and may lead to diseases such as pneumonia and asthma. pollution? Less severe symptoms caused by ozone pollution include burning eyes, dry throat, and headache. How do you know if ozone levels in your community are safe? You may have seen an Air Quality Index reported in your newspaper or on television. When the index is at an unhealthy level, people with breathing problems are cautioned to avoid outdoor activities. The table below shows the index along with ways to protect your health when ozone is high.

Air Quality Index

Air Quality Air Quality Protect Your Health Inndex

Good 0–500 No health impacts occur. Picture This Moderatte 51–1000 People with breathing problems should limit outdoor exercise. 4. Determine If the Air Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright Quality Index were reported Unhealthy for 1011–1505 Everyone, especially children and elderly, should to be at 75, what would the certain people not exercise outside for long periods of time. air quality be? Unhealthy 1511–2000 People with breathing problems should avoid outdoor activities.

288 Our Impact on Water and Air How does carbon monoxide affect people? Carbon monoxide contributes to air pollution. Carbon monoxide is a colorless, odorless gas found in car exhaust. This gas can make people ill, even in small amounts, because it replaces oxygen in the blood. This can cause chest pains and breathing difficulty. How does acid rain affect your lungs? When you breathe the humid air from acid rain, acid is inhaled deep into your lungs. This may cause irritation and reduce your ability to fight respiratory infections. When you 5. Infer What tissues and breathe, oxygen travels from the air to your lungs. Lungs organs are more likely to be damaged by acid rain cannot move oxygen into blood easily. harmed by air pollution? This puts stress on your heart. How do particles in the air harm the lungs? Particulate (par TIH kyuh luht) matter also harms the lungs. Particulate matter consists of fine particles such as dust, pollen, mold, ash, and soot that are in the air. It comes from forest fires, exhaust from trucks and buses, smoke from factories, or even dust picked up by the wind. Particulate matter ranges in size from large, visible bits of dust and soil to microscopic particles that form when substances are burned. Small particles are most dangerous because they can travel deeper into the lungs. When particulate matter is breathed in, it can irritate and damage the lungs, causing breathing problems. Reducing Air Pollution Air pollutants cross the borders between states and countries, going wherever the wind carries them. This makes them difficult to control. Even if one state or country reduces its air pollution level, pollutants from another state or country can blow across the border. For example, burning coal in midwestern states causes acid rain in the northeastern United States and Canada. When states and nations cooperate, pollution problems can be reduced. People from around the world have met on 6. Explain Why do states and countries find air several occasions to try and eliminate some kinds of air pollution difficult to control?

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright pollution. At one meeting in Montreal, Canada, an agreement called the Montreal Protocol was written to stop making and using CFCs by 2000. In 1989, the 29 countries that used 82 percent of CFCs signed the agreement. By 1999, 184 countries had signed it.

Reading Essentials 289 How has the United States reduced air pollution? The United States Congress has passed several laws to protect the air. One was the Clean Air Act of 1990. It helps to reduce air pollution from cars, power plants, and other industries. The Clean Air Act is summarized in the table below.

Clean Air Regulations

7. Predict Look at the chart Urban air All cars manufactured since 1996 must reduce nitrogen on this page. What might pollution oxide emissions by 60 percent and hydrocarbons by people do to reduce air pollutants even further? 35 percent from their 1990 levels. Acid rain Sulfur dioxide emissions had to be reduced by 14 million tons from 1990 levels by the year 2000.

Airborne ttoxins Industries must limit the emission of 200 compounds that cauuse cancer and birth defects.

Ozone-depleting Industries were required to immediately cease production chemicals of many ozone-depleting substances in 1996.

The Clean Air Act has helped decrease the amount of some pollutants released into the air each year, as shown in the ﬁgure below. However, millions of people in the United States still breathe unhealthy air.

Pollutants Released in the United States 50,000 1985 1994 Picture This 40,000 8. Analyze Look at the 2000 graph. Describe the overall 30,000 pattern in the amount of air pollutants released from 20,000 1985 to 2000. 10,000

0 Smog-producing Particulate Sulfur Total tons released per year substances matter dioxide Air pollutant

How can emissions be reduced? Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright More than 80 percent of sulfur dioxide emissions come from power plants that burn coal with a high sulfur content. When coal is burned, sulfur dioxides combine with moisture to form sulfuric acid, causing acid rain.

290 Our Impact on Water and Air Scrubbers Sulfur dioxide can be removed from power plant emissions by passing the smoke through a scrubber. A scrubber causes the gases to react with a limestone and water mixture. Another way to decrease the amount of sulfur dioxide is by burning coal that contains less sulfur. Electrostatic Separators Electric power plants that burn 9. Identify What substance do scrubbers remove from fossil fuels release particulates into the atmosphere. The power plant smoke? particulate matter can be removed from smoke with a pollution-control device called an electrostatic separator. This device acts like a magnet for smoke particles. Plates in the separator give the smoke particles a positive charge. The positively-charged smoke particles then stick to negatively-charged plates in the separator. How can pollution from cars, trucks, and buses be reduced? Recent improvements in car design, as well as the use of emission-control devices such as catalytic converters, have reduced car emissions significantly. The gasoline that we use today gives off less pollution than the gas used in the past. Future advances in technology might help to reduce emissions further. This is important because Americans are driving more today than they did in the past. More time spent driving leads to more traffic jams. Cars and trucks F T OC A U C Annually Assessed produce a lot of pollution when they are stopped in traffic. S F Benchmark Check Can you help reduce air pollution? SC.D.2.3.2 The Clean Air Act can work only if we all cooperate. Cleaning the air takes money, time, and effort. How might ✔ 10. Identify two ways you can reduce air you help reduce air pollution? You might change your pollution. lifestyle by walking, riding a bike, or using public transportation to get to a friend’s house instead of asking for a car ride. You also can set the thermostat in your home lower in the winter and higher in the summer. Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Companies, a division of The McGraw-Hill © Glencoe/McGraw-Hill, Copyright

Reading Essentials 291 After You Read Mini Glossary acid: substance with a pH lower than 7 pH scale: scale used to measure the amount of acid in a acid rain: acidic moisture, with a pH below 5.6, that falls to substance Earth as rain or snow photochemical smog: hazy, yellow-brown blanket of base: substance with a pH above 7 smog found over cities that is formed with the help of carbon monoxide: colorless, odorless gas that reduces the sunlight, contains ozone near Earth’s surface, and can oxygen content in the blood, is found in car exhaust, and damage lungs and plants contributes to air pollution scrubber: device that removes sulfur dioxide emissions from particulate matter: fine solids such as pollen, dust, mold, coal-burning power plants ash, and soot in the air that can irritate and damage lungs when breathed in

1. Review the terms and their deﬁnitions in the Mini Glossary. Write one sentence about air pollution using two vocabulary words.

2. Complete the concept map to show the types of air pollution. Air Pollution

Smog Acid Rain CFCs

forms from forms when released from

End of Visit ﬂ7.msscience.com to access your textbook, interactive Section games, and projects to help you learn more about air pollution.

292 Our Impact on Water and Air