Life Science Worksheet
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Life Science Worksheet GRADE LEVEL: Eight Topic: Cells Grade Level Standard: 8-1 Apply an understanding of cells to the functions of multicellular organisms. Grade Level Benchmark: 1. Demonstrate evidence that all parts of living things are made up of cells. (III.1.MS.1) Learning Activity(s)/Facts/Information Resources Central Question: What are cells? 1. Compare and contrast cell structure and processes. Saginaw/Midland County Science Curriculum pages 2. “Looking At Yeast Cells” - Note how rapidly yeast cells 1483-1490. increase in number. 3. “Cellebration” Activity is attached Process Skills: New Vocabulary: plants, animals, tissues, organs, organ system, paramecium, elodea leaf cells, onion skin cells, human cheek cells 1 LOOKING AT YEAST CELLS OBJECTIVE Students will identify the basic functions of a cell. SCIENCE PROCESSES Observing Measuring Communicating TEACHER SUGGESTIONS Introduction of cell division and growth. Experiment may be extended for several lessons. DESCRIPTION Looking at yeast cells and observing their growth. GROUP SIZE Dependent on number of microscopes EQUIPMENT AND MATERIALS Covered glass container (quart jars) Microscopes Slides and cover slides 1/4 teaspoon yeast, powdered-dry Eye droppers 1 pint warm water Table sugar PROCEDURE At least 12 hours before class, make up the following two solutions: Mixture # 1 1/4 teaspoon powdered yeast 1 pint warm water 1. Place mixture in a quart jar with a cover and let stand until dissolved. 2. Mix thoroughly each time before using. 3. Mixture should last one week, then a new solution should be made. 2 Mixture # 2 1 cup water 1 tablespoon table sugar 1 tablespoon mixture # 1 (yeast and water) 1. Place in a jar and mix. 2. Cover loosely. 3. Allow to stand for 12 hours so that the yeast cells will begin to divide. NOTE: At the start the yeast cells will divide rapidly in this mixture, but will stop dividing about four days later. EVALUATION Discussion of questions on the following pages. These pages are to be duplicated for the students. ADDITIONAL RESOURCE A Resource Book for the Biological Science, Harcourt, Brace, and World, Inc. TAKEN FROM Science in a Sack 3 LOOKING AT YEAST CELLS Make a slide using a small drop of yeast and table sugar mixture and a cover slip. 1. What does a yeast cell look like? 2. Draw a picture of several cells. 3. Can you tell the difference between a yeast cell and a small air bubble? 4. How big is a yeast cell? 4 EXAMINING YEAST CELLS THE NEXT DAY The next day make another slide of the yeast and table sugar mixture and examine it. 1. Do you notice any differences in the size of the cells? 2. If so, are the cells larger or smaller than before? 3. Is there any difference in the number of cells in the area you can see? 4. If you think there is a change in the number of cells, how can you be sure? 5 HOW RAPIDLY DO YEAST CELLS INCREASE IN NUMBER? 1. Why is it important to shake or stir the mixture of yeast and table sugar before taking a sample? Examine the slide you made using a microscope: 2. How many yeast cells did you count in the area you can see? 3. What time was it when you made the count? 4. If your microscope has more than one eyepiece, which one did you use? 5. Which objective lens did you use? 6. Why must you use the same lenses each time you make a count? Now move the slide and count another group of cells: 7. How many cells did you count this time? 8. Why is it important to count more than one area of your sample? 9. What is the average of the counts you have made? 6 CELLEBRATION You are going to examine a variety of cells under the microscope. Remember that the thinner the specimens are, the clearer the cells will appear. All of the specimens must be wet mounted. This means that you must be sure that the specimen is wet, and then you must press it flat against the slide. Add the appropriate dye, spread it evenly over the specimen, and set a cover slip on top. Tap the cover slip gently to remove any bubbles. Examine the specimen under LOW POWER ONLY. 1. ELODEA LEAF. Elodea is a pond plant. No stain is necessary. Notice the brick-shaped cells. The green dots are chloroplasts, which make and store chlorophyll (a chemical that enables plants to manufacture food). Draw several cells showing all of the detail. 2. ONION EPIDERMIS. Break a piece of onion and peel it back to remove the thin, transparent outer layer. Stain with two drops of iodine. Notice the large, narrow cell. The nuclei appear as tiny brown dots. Draw the entire field of view. 3. POTATO CELLS. Use a razor blade to shave off a paper-thin slice of potato. Stain with one drop of iodine. After about 15 seconds, (1) rinse it carefully, being sure not to lose the potato slice. Draw several of the large potato cells, showing the starch grains (which look like bunches of purple grapes). 4. CELERY STALK. Use a razor blade to cut a paper-thin slice across the stem. Add a drop of methylene blue stain. Notice that each vein is actually composed of a bundle of tubes. Draw a vascular bundle (vein) and the cells surrounding it. 5. ICE PLANT EPIDERMIS. Break an ice plant “leaf” and peel off a piece of (2) thin outer skin. Stain with one drop of methylene blue. Notice the stoma with their two guard cells. These look much like cat’s eyes. Draw a few stomata, their guard cells, and the cells surrounding them. 6. CHEEK EPITHELIUM. Gently scrape the inside of your cheek with a clean applicator. Smear the stuff on the end of a stick on the slide. Add one drop of methylene blue. Draw the tiny epithelium cells which look like irregularly shaped pancakes with a blueberry (the (3) nucleus) in the center. You might have to look around for quite a while to find a good group of cells. (4) (5) (6) 7 Assessment Grade 8 CELLS Classroom Assessment Example SCI.III.1.MS.1 Based on all the cell samples they have observed, students will create a product providing evidence that all living things are made of cells. This presentation should also highlight one scientist from the timeline and explain his or her contributions. Students may select from a variety of presentation mediums, including illustrations, multimedia presentations, models, posters, prepared slides, or informational books. Students will present their product to the class and explain characteristics of the different cells. (Give students rubric before activity.) Scoring of Classroom Assessment Example SCI.III.1.MS.1 Criteria Apprentice Basic Meets Exceeds Explanation of Provides a vague Provides a brief Provides an Provides an cells explanation. explanation. accurate, detailed extensive, explanation. detailed explanation. Evidence of cells Shows an Shows one or two Shows multiple Shows detailed example of a examples of cells. examples of cells. examples of a single cell. variety of cells. Explanation of Selects a scientist, Selects a scientist Selects a scientist Selects more than scientific but omits the and vaguely and explains his one scientist and contribution explanation of his explains his or her or her gives a detailed or her contribution. contribution. analysis of their contribution. contributions. 8 Life Science Worksheet GRADE LEVEL: Eight Topic: Cells Grade Level Standard: 8-1 Apply an understanding of cells to the functions of multicellular organisms. Grade Level Benchmark: 2. Explain why and how selected specialized cells are needed by plants and animals. (III.1.MS.2) Learning Activity(s)/Facts/Information Resources Central Question: Why are specialized cells needed in plants and animals? 1. “Respiration—Photosynthesis” Saginaw/Midland County Science Curriculum. Pages 2. “What Do Green Leaves Breathe Out”/“How is the 1525-1526, 1534-1535, 1537- Green Produced?” 1541. 3. “The Water Sucking Roots” Activity is attached Process Skills: New Vocabulary: reproduction, photosynthesis, transport, movement, disease fighting, red blood cells, white blood cells, muscle cells, bone cells, nerve cells, egg/sperm cells, root cells, leaf cells, stem cells 9 RESPIRATION PHOTOSYNTHESIS Presence of CO² Presence of O OBJECTIVE This activity is appropriate for all ages. It works well as a demonstration or a hands on activity. It shows the presence of carbon dioxide in our breath and the presence of oxygen in plant respiration. TERMS Photosynthesis — the process in which the energy of sunlight is trapped by chlorophyll an used to make food. Respiration — the process by which food is broken down and energy is released. TIME Part one - 15 minutes Part two - 1 to 2 hours BACKGROUND Photosynthesis is the process by which green organisms make food. An organism that makes food is a producer. Green plants are producers. Photosynthesis is the source of food for almost every other organism. In photosynthesis, carbon dioxide and water are combined with the aid of energy from light. The products of photosynthesis are sugars and oxygen. Respiration is another plant process. The cell process of respiration results in a release of energy from food. The energy from respiration is used for all the activities of the cells metabolism. Carbon dioxide and water are products of respiration. MATERIALS H2O Phenol red indicator (purchase at pool supply store) Aquatic plants work best, however, carrot tops, grass, and other plants do work Light source Test tube Cork Straw PROCEDURE # 1 1. Half fill a test tube with water. 2. Add phenol red, about two drops, and mix. 3.