angiosperm (AN-jee-uh-sPURM) A A that has and produces en- abiotic factor (AY-by-AHT-i hk) closed in . (p. 379) A nonliving physical or chemical part of an . (p. 474) Animalia (AN-U h-MAL-yu h) Part of a classification that divides all living things into six kingdoms. Animalia includes The process of using to move materials multicellular , from and to through a . (p. 60) and microbes, that rely on for energy. (p. 223) A characteristic, a behavior, or any inherited trait that makes a able to survive and reproduce in a A that can block the growth and reproduc- particular environment. (p. xxxvii) tion of . (p. 65 7) A physical or psychological need for a -forming A produced by some white cells to at- substance, such as alcohol or drugs. (p. 722) tack specific foreign materials. (p. 651) adolescence (Ao- u hi-EHS-uhns) The stage of life from the a begins A particular substance that the body recognizes as to mature sexually to adulthood. (p. 711) foreign and that stimulates a response. (p. 654) dulthood appendicular (AP-u hn-DIH K-yu h-lu hr) he stage of life that begins once a com- The of the skeleton that to allow letes movement, such as arm and leg bones. (p. 592) its growth and reaches sexual maturity. (p. 712) (AH R-kee- u h) Single-celled organisms without nuclei that can that live mostly in and use as survive in extreme environments. Archaea is a plural a source of energy. Algae is a plural word; the singu- word; the singular is archaean. (p. 290) lar is alga. (p. 303) Archaea (AH R-kee- u h) (uh-LEEL) Part of a classification system that divides all living An alternate of a for a specific trait or things into six kingdoms. Kingdom Archaea includes gene product. (p. 103) microscopic single-celled organisms with a distinctive that allows them to live in extreme environments. (p. 223) A cold-blooded that in water and breathes with gills when it is young; as an , artery it moves onto and breathes air with . A blood vessel with strong walls that carries blood (p. 439) away from the . (p. 645) ancestor A distant or early form of an from which later forms descend. (p. 189) An animal with an , a seg- mented body, and jointed legs. (p. 414) asexual binomial The process by which a single organism produces (by-NOH-mee-uhl NOH-mu hn-KLAY-c h u h r) that have the same genetic material. The two-part naming system used to identify (p. 88) species. The first part of the name is the , and the second part of the name is the species. (p. 212) The smallest of an element that has the chemical properties of that element. The number and of living things found on or within an ecosystem. (p. 555) autonomic The part of the nervous system that controls involun- biology tary action and responses. (p. 683) The scientific study of life and all living things; , biology, and are examples of bio- (AW-t u h-TRAHF) logical . An organism that captures energy from sunlight and uses it to produce energy-rich compounds, (BY-OHM) usually through the process of . A region of Earth that has a particular and (p. 324) certain types of . Examples are tundra, , , , temperate and tropical . axial skeleton (p. 494) The central part of the skeleton, which includes the cranium, the spinal column, and the ribs. (p. 592) biotic factor (by-AHT-i h k) A living thing in an ecosystem. (p. 494)

B blood bacteria (ba k-TEE R-ee-uh) A fluid in the body that delivers and other A large group of one-celled organisms that materials to cells and removes and sometimes . Bacteria is a plural word; other wastes. (p. 641 ) the singular is bacterium. (pp. 14, 725) Bacteria (bak-TEER-ee-uh) A layer of in some that lies be- Part of a classification system that divides all living neath the . It insulates the animal from cold and things into six kingdoms. Kingdom Bacteria includes stores reserve energy. (p. 456) microscopic single-celled organisms found in many environments. Bacteria can be associated with disease in other organisms. (p. 223) A process of in which an organism develops as an outgrowth of the . behavior Each can grow into a new organism, breaking An organism’s action in response to a . (p. free and becoming separate and independent. 334) (p. 89)

binary A form of asexual reproduction by which some singl- c ecelled organisms reproduce. The genetic material capillary is copied, and one cell divides into two indepen- A narrow blood vessel that connects arteries with dent cells that are each a copy of the original cell. veins. (p. 645) such as bacteria reproduce by binary fission. (pp. 89, 284) (KAHR- boh-HY-drayt) A of made up of subunits of and used for energy and structure. (p. 42) carbon childhood The continuous movement of carbon through Earth, The stage of life after infancy and before the begin- its , and the living things on Earth. ning of sexual maturity. (p. 7 10) (p. 482) (KLAWR-uh-f i h l) A -absorbing chemical, a , that traps the The maximum size that a can reach in an energy in sunlight and converts it to chemical ecosystem. (pp. 242, 529) energy. Found in of plant cells and the cells of other photosynthetic organisms. (p. 48) cell The smallest unit that is able to perform the basic (KLAW R-u h-PLAST) functions of life. (p. xxxi) An in a that contains chlorophyll, a chemical that uses the energy from sunlight to make . (p. 23) The normal sequence of growth, maintenance, and in a cell. (p. 80) The physical struture in a cell that contains the cell’s genetic material. (p. 75) The outer boundary of the , a layer that controls what enters or the cell; a protective covering enclosing an entire cell. (p. 20) The group of organs, consisting of the heart and blood vessels, that circulates blood through the cellular body. (p. 641) A process in which cells use oxygen to release energy stored in sugars. (pp. 50, 325, 615) classification The systematic grouping of different types of - isms by their shared characteristics. (p. 204) A protective outer covering that lies just outside the cell membrane of plant cells. (p. 2 1) The process of using DNA technology to produce an offspring that is genetically identical to its one The and . The central nervous parent. (p. 154) system communicates· with the rest of the nervous system through electrical signals sent to and from cnidarian (ny-DAI R-ee -uhn) . (p. 680) An invertebrate animal such as a that has a body with radial , tentacles with stinging chemical energy cells, and a central internal cavity. (p. 400) Energy that is stored in the chemical composition of . The amount of chemical energy in a sub- (ku h-MEHN-su h-uHz-uhm) stance depends on the types and arrangement of its An between two species in which one . When or gasoline burns, chemical en- species benefits without harming the other; a type of ergy produces heat. The energy used by the cells in . (p.523) your body comes from chemical energy in the you eat. (p. 47) All the that live and interact with each chemical reaction other in a particular place. The community can live The process by which chemical changes occur. In a in a place as small as a pond or a park, or it can live chemical reaction, atoms are rearranged, and in a place as large as a or the . chemical bonds are broken and formed. (p. 42) (p. 512) compact cytoplasm (SY-t u h-PLAZ-u hm) The tough, hard outer layer of a bone. (p. 591) A thick, gelatin-like material contained within the cell membrane. Most of the work of the cell is carried out in the cytoplasm. (p. 20) The struggle between two or more living things that depend on the same limited . (p. 519) D competitor A species characterized by a relatively longer life gathered by observation or experimen- span, with relatively few offspring, when compared tation that can be used in calculating or reasoning. with an opportunist species. (p. 256) Data is a plural word; the singular is datum. compound (dih-SIHJ-oo-u hs) A substance made up of two or more different types A term used to describe and that drop of atoms. their leaves when comes; examples are , , and trees. (p. 497) coniferous (koh-NIHF-uhr-uhs) A term used to describe cone-bearing trees and shrubs that usually keep their leaves or needles dur- An organism that feeds on and breaks down dead ing all the seasons of the ; examples are , plant or animal matter. (pp. 291, 489) , and trees. (p. 496) density conservation A property of matter representing the mass The process of saving or protecting a natural per unit volume. resource. (p. 563) dermis The inner layer of the skin. (p. 660) A living thing that gets its energy by other living things in a ; consumers are also dichotomous key (dy-KAHT-uh-m u hs) called . (pp. 330, 488) A of questions, each with only two answers, that can be used to help identify an organism’s ge- nus and species. (p. 216) A term used to describe an interaction between two or more living things in which they are said to work (di h-FY OO-z h u hn) together. ( p. 5 21 ) The tendency of a substance to move from an area of higher to an area of lower concen- cycle tration .(p. 56) n. A series of events or actions that repeat them- selves regularly; a physical and/or chemical process in which one material continually changes locations The process of breaking down food into usable ma- and/or forms. Examples include the water cycle, the terials. (p. 622) , and the cycle. v. To move through a repeating series of events or digestive system actions. The in the body that work together to transform the energy and materials in food into (sY-to h-kuh-NEE-si hs) forms the body can use. (p. 622) The division of a parent cell’s cytoplasm following . (p. 81) diversity A term used to describe the quality of having many differences. Biodiversity describes the great variety and many differences found among living things. DNA emigration The genetic material found in all living cells that In population studies, the movement of contains the information needed for an organism to out of an ecosystem. (p. 251) grow, maintain itself, and reproduce. Deoxyribonucleic acid (dee-AHK-see-RY-boh-noo-KL E E- i hk). (p. 74) A group of organs called and the they produce that help regulate conditions inside the body. (p.686) One of three divisions in a classification system based on different types of cells. The six kingdoms endoskeleton of living things are grouped into three domains: Ar- An internal support system; such a skeleton made of chaea, Bacteria, and Eukarya. (p. 221) bone is a distinguishing characteristic of ver- tebrate . (p. 429) dominant A term that describes the allele that determines the endotherm of an organism when two An animal that maintains a constant body tempera- different copies are present in the . (p. 107) ture. (p. 446)

energy E The ability to do work or to cause a change. For ex- ample, the energy of a moving bowling ball knocks An invertebrate sea animal with a spiny skeleton, a over pins; energy from food allows animals to move water vascular system, and tube feet. (p. 411) and to grow; and energy from the heats Earth’s surface and atmosphere, which causes air to move. ecology The scientific study of how living things interact with energy pyramid each other and their environment. (p. 473) A model used to show the amount of energy avail- able to living things in an ecosystem. (p. 492) ecosystem All the living and nonliving things that interact in a environment particular environment. An ecosystem can be as Everything that surrounds a living thing. An environ- small as a meadow or a swamp or as large as a for- ment is made up of both living and nonliving factors. est or a desert. (p. 473) (p. xxxv) An animal whose body changes with The outer layer of the skin. (p. 660) environmental conditions. (p. 442) estuary The lower end of a river where it meets the ocean A reproductive cell () that forms in the and fresh and mix. (p. 500) reproductive organs of a female and has just a single copy of the genetic material of the parent. eukaryotic cell (yoo-KAR-ee-AHT- i h k) (p. 118) A cell in which the genetic material is enclosed within a nucleus, surrounded by its own membrane. element (p. 20) A substance that cannot be broken down into a simpler substance by ordinary chemical changes. An element consists of atoms of only one type. The process through which species change over time; can refer to the changes in a particular popu- (EHM-bree-oH) lation or to the formation and of species A , plant or animal, in its earli- over the course of Earth’s history. (p. 177) est stages of development. (pp. 370, 697) exoskeleton Fungi (FUHN-jy) The strong, flexible outer covering of some inverte- Part of a classification system that divides all living brate animals, such as . (p. 415) things into six kingdoms. Kingdom Fungi includes multicellular and and single- celled . (p. 223) An organized procedure to study something under controlled conditions. (p. xl) G extinction gamete The permanent disappearance of a species. (p. A or , containing half the usual num- xxxvii) ber of of an organism (one chromo- some from each pair), which is found only in the reproductive organs of a plant or animal. (p. 118) F gene A chemical process by which cells release energy The basic unit of that consists of a segment from sugar when no oxygen is present. (p. 52) of DNA on a chromosome. (pp. 102, 193) fertilization Part of the process of in which a The scientific process in which DNA is separated male reproductive cell and a female reproductive from an organism, changed, and then reinserted into cell combine to make a new cell that can develop the same or a different organism. (p. 151) into a new organism. (pp. 118, 320, 697) genetic material The DNA that is present in all living cells The developing human embryo from eight weeks to and contains the information needed for a cell’s . (p. 698) growth, maintenance, and reproduction. . (JEE-no hm) The reproductive structure of an angiosperm, con- All the DNA of an organism, including its ; the taining male and female parts. (p. 380) genetic material of an organism. (p. 154) food chain genotype (JEHN-uh-TYP) A model used to show the feeding relationship The genetic makeup of an organism; all the genes between a single producer and a chain of consum- that an organism has. (p. 106) ers in an ecosystem. In a typical food chain, a plant is the producer that is eaten by a consumer, such genus as an ; then the insect is eaten by a second The first part of a binomial name that groups consumer, such as a . (p. 490) together closely related species. The genus includes all species of small . (p. 212) A model used to show a feeding relationship in (JUR-muh-NAY-shuhn) which many food chains overlap in an ecosystem. The beginning of growth of a new plant from a (p. 490) or a . (p. 371) The imprint or hardened remains of a plant or animal In mammals, the period of time spent by a develop- that lived long ago. (p. 169) ing offspring inside the ’s body. (p. 458) fruit gill The ripened of a that contains A respiratory organ that filters oxgen dissolved in the seeds. (p. 380) water. (p. 409) hypothesis An organ in the body that produces a specific sub- A tentative explanation for an observation or stance, such as a . (p. 687) phenomenon. A hypothesis is used to make tenta- tive predictions. (p. xl) A sugar molecule that is a major energy source for most cells, produced by the process of I, J, K photosynthesis. (p. 47) immigration In population studies, the movement of an organism (JIHM-nuh-sPURM) into a range inhabited by individuals of the same A plant that produces seeds that are not enclosed in species. (p. 251) flowers or fruit. (p. 374) A group of organs that provides protection against H disease-causing agents. (p. 651) The in which a living thing gets all that it needs to live; examples include a desert, a to a disease. Immunity can result from reef, and a freshwater lake. (p. 510) formed in the body during a previous at- tack of the same illness. (p. 656) heredity The passing of genes from to offspring; the incubation genes are expressed in the traits of the offspring. The process of keeping warm by bodily heat (p. 102) until they hatch. (p. 451) (HEHT-uhr-uh-TRAWF) infancy An organism that consumes other organisms to get The stage of life that begins at birth and ends when energy. (p. 330) a baby begins to walk. (p. 710) insect A sleeplike state in which certain animals spend the An arthropod with three body segments, six legs, winter. Hibernation reduces an animal’s need for two antennae, and compound . (p. 417) food and helps protect it from cold. (p. 336) (ihn-TEHG-yu-MEHN-t uh-ree) (HOH-mee-oh-STAY-sihs) The body system that includes the skin and its as- A condition needed for and functioning in sociated structures. (p. 659) which an organism or cell maintains a relatively stable . (p. 588) interaction The condition of acting or having an influence upon hormone something. Living things in an ecosystem interact A chemical that is made in one organ and travels with both the living and nonliving parts of their envi- through the blood to another organ. (p. 687) ronment. (p. xxxv) cell A cell that a infects and uses to make copies of The period in the cell cycle in which a cell grows, itself. (p. 298) maintains itself, and prepares for division. (p. 81) hyphae invertebrate Threadlike tubes that form the structural parts of the An animal that has no backbone. (p. 395) body of a . Hyphae is a plural word; the sin- gular is . (p. 339) involuntary muscle A muscle that moves without conscious control. (p. 600) (my-OH-sihs) L A part of sexual reproduction in which cells divide to larva form sperm cells in a male and egg cells in a female. A free-living early form of a developing organism Meiosis occurs only in reproductive cells. that is very different from its adult form. (p. 398) (pp. 119, 320) law In science, a rule or principle describing a physi- A period of about five days during which blood and cal relationship that always works in the same way tissue exit the body through the . (p. 695) under the same conditions. The law of conservation of energy is an example. The transformation of an animal from its larval form (LY-kuhn) into its adult form. (p. 418) An organism that results from a close association between single-celled algae and fungi. (p. 342) A very small organism that can be seen only with a . Bacteria are examples of microorgan- A factor or condition that prevents the continuing isms. (pp. 282, 724) growth of a population in an ecosystem. (pp. 252, 528) microscope An instrument that uses glass lenses to magnify an object. (p. 12) A type of molecule made up of subunits of fatty acids. are found in the , oils, and waxes migration used for structure and to store energy. (p. 43) The movement of animals from one region to an- other in response to changes in the seasons or the environment. (p. 336) A respiratory organ that absorbs oxygen from the air. (p. 409) mitochondria (MY-t uh-KAWN-dree-uh) that release energy by using oxygen to M break down sugars. (p. 23) A warm-blooded vertebrate animal whose young mitosis feed on milk produced by the mother’s mammary The phase in the cell cycle during which the nucleus glands. (p.455) divides. (p. 81) mass mobile A measure of how much matter an object is made Able to move from place to place. (p. 402) of. molecule mass extinction A group of atoms that are held together by covalent One of several periods in Earth’s history when large bonds so that they move as a single unit. numbers of species became extinct at nearly the same time. (p. 174) mollusk An invertebrate animal with a soft body, a muscular matter foot, and a mantle. Many mollusks have a hard outer Anything that has mass and volu!Jle. Matter exists shell. (p. 408) ordinarily as a solid, a liquid, or a gas. molting The process o f an arthropod shedding its exoskel- eton to allow for growth. (p. 415) multicellular nucleus (NOO-klee-uhs) A term used to describe an organism that is made The structure in a eukaryotic cell that contains the up of many cells. (p. 11) genetic material a cell needs to reproduce and function. (p. 20) multicellular organism An organism that is made up of many cells. (p. 173) (NOO--uhnt) A substance that an organism needs to live. Ex- muscular system amples include water, , and materials that The muscles of the body that, together with the skel- come from the breakdown of food . (p. 621) etal system, function to produce movement. (p. 599) The study of the materials that nourish the body. (p. Any change made to DNA. (p.145) 716) (MY OO-choo-u h-uHz- u hm) interaction between two species in which both 0 benet; a type of symbiosis. (p. 522) offspring T he new organisms produced by one or two parent organisms. N opportunist Any type of matter or energy from Earth’s environ- A species characterized by a relatively short life ment that humans use to meet their needs. (p. 548) span, with relatively large quantities of offspring, as compared with a competitor species. (p. 255) The process through which members of a species organ that are best suited to their environment survive and A structure in a plant or an animal that is made up reproduce at a higher rate than other members of of different tissues working together to perform a the species. (p. 181) particular function. (pp. 30, 316, 587) organelle (AWR-g uh-NEHL ) A cell. (p. 681) A structure in a cell that is enclosed by a membrane and that performs a particular function. (p. 20) niche (nihch) The role a living thing plays in its habitat. A plant is a organism food producer, whereas an insect both consumes An individual living thing, made up of one or many food as as provides food for other consumers. cells, that is capable of growing and reproducing. (p. 511) (p. xxxi) cycle The continuous movement of nitrogen through A group of organs that together perform a function Earth, its atmosphere, and the living things on Earth. that helps the body meet its needs for energy and (p. 483) materials. (p. 588) nucleic acid (noo-KLEE- i h k) (ahz-MO H-sihs) A type of molecule, made up of subunits of nucleo- The movement of water through a membrane from , that is part of the genetic material of a cell an area of higher concentration to an area of lower and is needed to make . DNA and RNA are concentration. (p. 59) nucleic acids. (p.43) P, Q The first species to move into a lifeless environment. parasite An organism that absorbs from the body of plants another organism, often harming it in the process. like are typical pioneer species on land. (p. 291) (p. 530) (PAR-uh-suh-TIHz-u hm) A relationship between two species in which one An organ that transports materials between a preg- species is harmed while the other benefits; a type of nant female mammal and the offspring developing symbiosis. (p.523) inside her body. (p. 458) parent An organism that produces a new organism or Mostly microscopic organisms that drift in great organisms similar to or related to itself. (p. 93) numbers through bodies of water. (p. 305) Plantae (PLAN-tee) The movement of materials through a membrane Part of a classification system that divides all living without any input of energy. (p. 58) things into six kingdoms. Kingdom Plantae includes multicellular organisms, such as trees, grass, and , that are capable of photosynthesis, capturing An agent that causes disease. (p. 650) energy from the Sun. (p. 223) pedigree A chart that shows relationships, including two Tiny multicellular grains that contain the undevel- or more generations. (p. 147) oped sperm cells of a plant. (p. 372) percentage A ratio that states the number of an outcome The release of harmful substances into the air, wa- is likely to occur out of a possible 100 times. (p.112) ter, or land. (pp. 264, 555) peripheral nervous system population The part of the nervous system that lies outside the A group of organisms of the same species that live brain and spinal cord. (p. 682) in the same area. For example, a desert will have populations of different species of and peristalsis (P EHR- i h-STAWL-sihs) plants. (p. 510) Wavelike contractions of smooth muscles in the organs of the digestive tract. The contractions move food through the digestive system. (p. 622) A measure of the number of organisms that live in a given area. The population density of a city may be phenotype given as the number of people living in a square The observable characteristics or traits of an kilometer. (pp. 245, 550) organism. (p. 106) photosynthesis (FOH-toh-SIHN-t h i h-sihs) The study of the changes in the number of individu- The process by which plants and other als in a population and the factors that affect those producers use simple compounds and energy changes. (p. 241) from light to make sugar, an energy-rich compound. (pp. 48, 324, 487) The number of individuals of the same species that live in a given area. (p. 244) predator recessive An animal that hunts other animals and eats them. A term that describes an allele that is not expressed (pp. 335, 519) when combined with a dominant form of the gene. (p. 107) prey An animal that other animals hunt and eat. (pp. 335, 519) A type of blood cell that picks up oxygen in the lungs and delivers it to cells throughout the body. (p. 643) probability The likelihood or chance that a specific outcome will occur out of a total number of outcomes. (p. 112) In some organisms, the process by which certain cells produce new at the site of a producer wound or lost limb; also a form of asexual reproduc- An organism that captures energy from sunlight and tion. (p. 90) transforms it into chemical energy that is stored in energy-rich carbon compounds. Producers are a replication source of food for other organisms. (pp. 291, 487) The process by which DNA is copied before it con- denses into chromosomes. Replication takes place prokaryotic cell (pro h-KAR-ee-AWT- i h k) before a cell divides. (p. 137) A cell that lacks a nucleus and other organelles, with DNA that is not organized into chromosomes. (p. 20) A cold-blooded vertebrate that has skin covered with protein scales or horny plates and has lungs. (p. 440) One of many types-of made up of chams of subunits. Proteins control the chemi- resistance cal activity of a cell and support growth and repair. The ability of an organism to protect itself from a (p. 43) disease or the effects of a substance. (p. 729)

Protista (pro h-TIH S-tuh) respiration Part of a classification system that divides all living The physical and chemical processes by which a liv- things into six kingdoms. Kingdom Protista includes ing thing exchanges gases with the environment. In mostly single-celled organisms with cells similar to , cells take in oxygen and release those of the Plantae, Animalia, and Fungi kingdoms. the energy stored in carbon compounds. (p. 223) A system that interacts with the environment and Animal-like protists that eat other organisms or de- with other body to bring oxygen to the body caying parts of other organisms. Protozoa is a plural and remove carbon dioxide. (p. 613) word; the singular is protozoan. (p. 306) . RNA Punnett square A molecule that carries genetic information from A chart used to show all the ways genes from two DNA to a , where the genetic information is parents can combine and be passed to offspring; used to bring together amino acids to form a protein. used to predict all that are possible. Ribonucleic acid (RY-boh-noo-KL EE-ihk). (p. 138) (p. 110) s R ratio One of the thin, small, overlapping plates that cover A comparison between two quantities, often written most and and some other animals. (p. with a colon, as 3 : 4. (p. 112) 433) seed A plant embryo that is enclosed in a protective coat- A simple multicellular invertebrate animal that lives ing and has its own source of nutrients. (p. 370) attached to one place and filters food from water. (p. 397) The process of breeding plants and animals with spongy bone specific traits to produce offspring that have these Strong, lightweight tissue inside a bone. (p. 591) traits. (p. 151) spore sessile (SEH S-m) A single reproductive cell that can grow into a multi- The quality of attached to one ; not cellular organism. (p. 339) freemoving. (p. 397) stimulus sexual reproduction Something that causes a response in an organism A type of reproduction in which male and female or a part of the body. (pp. 327, 678) reproductive cells combine to form offspring with genetic material from both cells. (pp. 102, 320) succession (suh k- S E H S H- u hn) A natural process that involves a gradual change in the plant and animal communities that live in an A muscle that attaches to the skeleton. (p. 600) area. (p. 530) skeletal system sustainable The framework of bones that supports the body, A term that describes the managing of certain protects internal organs, and anchors all the body’s natural so that they are not harmed movement. (p. 590) or used up. Examples include maintaining clean and protecting top from erosion. smooth muscle (p. 566) Muscle that performs involuntary movement and is found inside certain organs, such as the . symbiosis (SIHM--OH-sihs) (p. 600) The interaction between individuals from two different species that live closely together. (p. 522) specialization The specific organization of a cell and its structure system that allows it to perform a specific function. (p. 28) A group of objects or phenomena that interact. A system can be as simple as a rope, a pulley, and a mass. It also can be as complex as the interaction The evolution of a new species from an existing spe- of energy and matter in the four parts of the Earth cies. (p. 184) system. . species A group of living things that are so closely related T that they can with one another and produce offspring that can breed as well. (p. xxxvii) The science of classifying and naming organisms. (p. 204) sperm A male reproductive cell (gamete) that forms in the technology reproductive organs of a male and has just a single The use of scientific knowledge to solve problems or copy of the genetic material of the parent. (p. 118) engineer new products, tools, or processes.

tentacle A long, slender, flexible extension of the body of certain animals, such as jellyfish. Tentacles are used to touch,move, or hold. (p. 400) theory vascular system (-kyuh-l u r) In science, a set of widely accepted explanations of Long tubelike tissues in plants through which wa- observations and phenomena. A theory is a ter and nutrients move from one part of the plant to well-tested explanation that is consistent with all another. (p. 359) available evidence. vein tissue A blood vessel that carries blood back to the heart. A group of similar cells that are organized to do a (p.645) specific job. (pp. 29, 316, 586) vertebrate trait An animal w ith an internal backbone. (p. 429) Any type of feature that can be used to tell two spe- cies apart, such as size or bone structure. vestigial organ (veh-STI HJ-ee-u h l) A physical structure that was fully developed and (TRAN-spuh-RAY-s h u hn) functional in an earlier group of organisms but is The movement of water vapor out of a plant and into reduced and unused in later species. (p. 190) the air. (p. 360) virus A nonliving disease-causing particle that uses the U materials inside cells to make copies of itself. A virus unicellular consists of genetic material enclosed in a protein A term used to describe an organism that is made coat. (pp. 286, 725) up of a single cell. (p.11) volume An amount of three-dimensional , often used An organism that is made up of a single cell. (p. to describe the space that an object takes up. 172) voluntary muscle urban A muscle that can be moved at w ill. (p. 600) A term that describes a city environment. musculo voluntario Un musculo que puede moverse a voluntad. voluntary nervous system The that govern consciously controlled A group of organs that filter waste from an function and movement. (p. 683) organism’s blood and excrete it in a liquid called urine. (p. 629) W, X, Y, Z urine water cycle Liquid waste that is secreted by the kidneys. (p. 629) The continuous movement of water through Earth, its atmosphere, and the living things on Earth. (p. 481) V vaccine A small amount of a weakened pathogen that is introduced into the body to stimulate the production of antibodies. (p. 656) variable Any factor that can change in a controlled experiment, observation, or model. (p. R30)