Download Comparing Plant and Animal Cells Lab Onion and Elodea Plant Cells

Name: _______________________________________________ Date: _________________________ Block: ________
Comparing Plant and Animal Cells Lab
due Friday, September 30th
Question
How are plant and animal cells alike? How are they different?
Objectives
In this lab, students will:
1. Observe plant cells from onions and elodea plants using a compound light microscope.
2. Observe animal cells from their own cheek using a compound light microscope.
3. Discover the similarities and differences between the two types of cells through careful observation.
Onion and Elodea Plant Cells
Procedure
1. Answer the following pre-lab questions.
a. What is the function of chloroplasts?
b. Name two structures found in plant cells but not in animal cells.
1)
2)
c. Name three structures found in both plant and animal cells.
1)
2)
3)
d. What structure surrounds the cell membrane (in plants) and gives the cell support?
2. Prepare a slide of onion cells.
a. Obtain a piece of onion from Ms. Rowlen.
b. Using the forceps (tweezers), peel off the membrane from the underside of the onion.
c. Lay the flat membrane on the surface of a clean glass slide.
d. Bring your slide to the table in front and ask Ms. Rowlen to add a drop of iodine. Be careful – iodine is a
dye that will stain your skin and clothes.
e. Allow Ms. Rowlen to then add a thin glass cover slip to your slide.
3. View the onion cells under the microscope, beginning at the low power objective and moving up.
a. When you are looking at these cells, you should find what resembles a brick wall, with each brick
representing a cell. The nucleus of these cells will be visible. Plant cells also have a rigid cell wall, outside
the cell membrane. These cell walls should also be visible.
4. Sketch the cells under the low power objective and under the high power objective in the space on the next page.
Be sure to pay attention to scale.
a. Identify the cell wall in your drawings.
b. Identify the nucleus in your drawings.
c. Identify the cytoplasm in your drawings.
Low Power Objective
High Power Objective
5. You may verify your findings with the prepared onion cell slides on the microscopes on the front desk.
6. View the elodea cells under the microscope using the prepared slide provided, beginning at the low power
objective and moving up.
a. When you are looking at these cells, you should find what resembles a brick wall, with each brick
representing a cell. The nucleus of these cells will not be visible, but you should see many chloroplasts
within each cell. Plant cells also have a rigid cell wall, outside the cell membrane. These cell walls should
also be visible.
7. Sketch the cells under the low power objective and under the high power objective in the space below. Be sure
to pay attention to scale.
a. Identify the cell wall in your drawings.
b. Identify the nucleus in your drawings.
c. Identify the cytoplasm in your drawings.
d. Identify the chloroplasts in your drawings.
Low Power Objective
High Power Objective
8. Answer the following questions.
a. Describe the shape and location of chloroplasts.
b. Why were no chloroplasts found in the onion cells? (Hint: Think about where one would find an onion.)
Human Cheek Cells
Procedure
9. Have Ms. Rowlen put a drop of methylene blue on a slide. Caution: Methylene blue will stain clothes and skin.
10. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
11. Stir the end of the toothpick in the stain and throw the toothpick away.
12. Have Ms. Rowlen place a coverslip onto the slide.
13. View your slide under the microscope. Once you have moved to the middle power objective, you should begin to
see cells. (These are light colored blobs with dark spots in them. Perfect circles with black outlines are air
bubbles.)
14. Sketch the cells under the low power objective and under the high power objective in the space below. Be sure
to pay attention to scale.
a. Identify the nucleus in your drawings.
b. Identify the cytoplasm in your drawings.
c. Identify the cell membrane in your drawings.
Low Power Objective
High Power Objective
15. Answer the following questions.
a. Why is the methylene blue necessary?
b. The light microscope used in the lab is not powerful enough to view other organelles in the cheek cell.
What parts of the cell were visible?
c. Does the cheek cell belong to a eukaryote or a prokaryote? How do you know?
d. Keeping in mind that the mouth is the first site of chemical digestion in a human. Your saliva starts the
process of breaking down the food you eat. Keeping this in mind, what organelle do you think would be
numerous inside the cells of your mouth? (We have not yet discussed this – so you will need to do some
research!)
Analysis
Venn Diagram
On the next page, create a Venn diagram of plant and animal cells. Remember, things that they have in common go into the
overlapping area, and things that are different go in the non-overlapping area.