Students will identify these animal cell structures: Students should properly answer the pre-activity cell membrane, nucleus. questions.

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1 WHAT DO PLANT & ANIMAL CELLS LOOK LIKE? Grade Levels: Time Frame: 2 periods Big Idea: Students will compare various plant epithelial cells (onion and elodea) with human epithelial cells (cheek lining and prepared skin slides), and begin to differentiate between structure and function of the cells. This can be done as part of a unit on the cell or a unit on the human body and epithelial tissue. Objectives/Outcomes/Expectations: Assessment: Students will demonstrate proper use of the microscope. Students should recognize and demonstrate proper technique. Students will demonstrate proper wet mount technique. Students will identify these animal cell structures: Students should properly answer the pre-activity cell membrane, nucleus. questions. Students will identify these plant cell structures: Students should be able to answer the questions cell membrane, cell wall, nucleus, vacuole, imbedded in the procedure. chloroplast. Students will identify differences between plant Students should be able to draw and properly and animal cell structures and relate this to label their own diagrams in the procedure. differences in function.

2 Materials Part 1: Onion Wedge Iodine Stain Elodea Sprig 2 Toothpicks 2 Slides 2 Coverslips Forceps Materials Part 2: Prepared Skin Slide Wright Stain 2 Slides 2 Toothpicks 2 Coverslips Procedures: Academic Adaptations Behavioral/Social Adaptations Assistive Technology PART 1 - Plant Cells: Onion & Elodea A. The curved pieces that form the layers of an onion are called scales. On the underside of each scale is a thin membrane called the epidermis. Remove one of the scales from your onion, and using forceps pull away the epidermis from the inner surface. Be careful not to wrinkle the mem-brane! B. Prepare a wet mount of the onion epidermis, using the toothpicks to smooth out any wrinkles. C. Examine the Epidermis (unstained) first with low power. Unstained specimens are often seen better with lower light adjust the microscope s diaphragm to reduce the light. -How many layers thick is the epidermis? -Draw the general shape of an epidermal cell here: D. Now you will stain the specimen. Remove the slide from the microscope stage. Place 1. Sometimes students who struggle academically need to not only have auditory cues (teacher class oral discussions), but also require visual cues(overheads, chalk boards, and/or topic related posters) to be successful in the regular classroom. In a lab such as this it might be useful to have the steps clearly written on 1. Stress the importance of safety procedures. Warn students that those observed breaking any safety rules will be excluded from this lab and required to do an alternative assignment. 2. Pair students with poor motor skills with a partner to help with drawing the cell diagrams. 3. To structure this activity, make up a worksheet on the background For students that may have difficulty looking through the eye piece of a microscope a projection

3 a drop of Iodine at the edge of one side of the coverslip. Draw the fluid underneath with a scrap of paper ** Iodine is toxic and it will stain! E. View the stained onion slide under low and then high power. - What does the nucleus look like? - Where in an individual cell is the nucleus found? - Draw a group of several cells under high power label the nucleus, cell wall, vacuole, cytoplasm F. Prepare a wet mount of a single leaf of Elodea (use a young leaf at the tip of the stem). - Are the chloroplasts moving or stationary? - In what way are these cells similar to the onion cells? - In what way are these cells different from the onion cells? - Draw a group of several cells under high power. Label the nucleus, cell wall, vacuole, and chloroplast. PART 2 Animal Cells: Skin Cross Section & Cheek Lining G. Scrape the inside lining of your cheek with toothpick. On a slide, place a drop of water & mix the tip of the toothpick with the water drop. Place a cover slip on top. H. Stain the cheek cells with Wright Stain the same way as in Part 1. an overhead and directly taught to the whole class. This will allow the students to become familiar with the big idea of the lesson as well as the expectations for this class period. Periodically the teacher can refer back to the overhead. 2. A teacher can include an organizer that allows students to self-check their progress. See handout L.17 questions. Make participating in the lab contingent on finishing the worksheet. microscope would be a good solution if available. If not still pictures or live web picture of the various cell would be a good alternative Instead of drawing the cell students with poor motor skills could be given a diagram of the cell with guides drawn for labeling. Or stickers that could be adhered to the correct parts of the cell.

4 I. Examine the slide under low power then under high power.- In the mouth, these cells would be joined in a sheet. Why are they scattered here?- Draw a few cells, and label the cell membrane, nucleus and cytoplasm J. Observe the prepared skin slide under low and then high power. - How does the shape of these cells compare to the cheek cells? - What structure do the cheek and animal cells not have that the plant cells did? - How does this relate to the function of the plant and animal cells? - Draw a group of the skin cells, label the nucleus, cell membrane, and cytoplasm. 3. The teacher can again use handout L.17 to assist in monitoring the lab/activity. Background Knowledge: Cells are the basic functional units of all living organisms. They may exist singly or in groups. When cells join together to take on a specialized function within a larger organism, they form a tissue. All cells fall into one of these two types: prokaryotic cells (has no nucleus), and eukaryotic cells (has a nucleus). Bacteria are prokaryotes. Plants, animals, fungi, protozoa and algae are eukaryotes. Animal and plant cells share many characteristics, but they also differ in several important ways. You will observe some of these similarities and differences in this lab. In this lab, you will look at epithelial cells (cells that form epithelial tissue) in both plants and animals. Epithelial tissue forms the skin of the outer body surfaces and the linings of inner surfaces. These cells are specialized for the protection of surfaces. The individual cells of these layers may be shaped like cubes, columns, or be flat - depending on their location and function. In this lab you will be looking at the epithelial tissue from two plant types: an onion & the water plant, elodea. You will then compare the plant cells to the cheek cells & skin cells of a human.

5 Questions: (Pre-Activity) Have students use cell diagrams & background reading to answer questions. (Some students with academic difficulties might not be able to read the text independently. Reviewing the features of the text might be an exercise that would benefit the whole class.)see accommodation folder for a Text Preview Worksheet 1. What is a cell? 2. What basic feature distinguishes plant and animal cells from bacteria? 3. Give an example of a prokaryotic organism: 4. Give an example of a eukaryotic organism: 5. What is a tissue? 6. What is the specialized purpose of epithelial tissue? 7. What three structures does a plant cell have that an animal cell does not have? Staging/Tips: - Have supplies set up at each lab table or station. - Have proper eye wear, aprons, and gloves for each student & stress the importance of safety when working with stains. - Demonstrate proper wet mount technique before activity. - Demonstrate proper staining technique also. This lesson was modified for science by the Science PK16 Leadership Team and accommodations were created by the Special Education and Assistive Technology PK16 Leadership Team Members. The development of all lessons was supported by funding from the PK16 UW System Technology Initiative Grant Project. The original source of the lesson was: Title: "What do Animal and Plant Cells Look Like?" Book Title: Modern Biology Laboratories Pages: p Year: 1989 Publisher: Holt, Rinehart, and Winston, Inc. Authors: none listed