Observing Plant and Animal Cells Lab
Please do not write on this sheet. Biology 112
You are now ready to begin observing eukaryotic cells. When you first look at the cells
of a plant or an animal through a microscope, they might just look like rows of boxes
squished together or dots within dots. There may appear to be nothing inside them. To
observe the parts of a cell more clearly, biologists usually add coloured stains of various
kinds.
In this lab, you will continue to develop your skills using the microscope to investigate
cells and you will learn how to use some microscopic stains. You will be observing cells from
onion skin, from your cheek and from another source, looking for any organelles which you
might be able to see.
This is a full lab report which has to include the sections listed below. Refer to your
class notes and the notes below on how to do each section. Because this is your first lab, I
have included questions to help you know what you should include in your
observations/results. These questions are numbered and written in bold.
Also note the Discussion questions. For this lab, the answers to these questions will
form the last section of your lab, “Discussion”. In a discussion or conclusion you never
include question numbers. Just write full sentences in a paragraph.
In this lab report, you have to include:
Title page
Introduction:
For the introduction to your lab report, include general information about the observation of
plant and animal cells under a microscope, organelles, and the use of microscopic staining.
State the purpose of this lab.
Materials:
List the materials you used. (Be specific. For example, say “250 ml glass beaker” not “a
beaker”.
Procedure:
Step-by-step what you did (numbered steps, 3rd person, past tense). Include an explanation
of how you prepared the onion cells, the cheek cells and any other sample you used. (See the
instruction sheet on the reverse.) Do not include the fact that you got set up a microscope,
got your materials, or cleaned up.
Results:
Observations: Make and record observations using the questions from the instruction sheet
on the reverse and any other observations that you feel are relevant. You may want to create
a table on which to record your observations.
Diagrams: Draw and label what you see when looking through the microscope. You will have
3 diagrams Remember to follow the instructions on biological diagrams.
Discussion:
See questions at end
Observing onion and cheek cells---Instructions
Materials:
microscope
cover slips (3)
tweezers
tap water
dilute iodine solution
section of leaf
microscope slide
dropper
small piece of onion
toothpick or Qtip
paper towel
scalpel
Part A - Procedure:
1. Set up the microscope and gather necessary materials (For this lab, you should wear
goggles and gloves, dress for a lab and tie long hair back.)
Q. 1. Obtain and record the field of view (in micrometers) of your microscope for the power
you are using.
2. Obtain a small piece of onion.
3. Use the scalpel and tweezers to gently remove a small piece of the thin “skin” from the
concave side of the piece of onion. This thin skin is epidermal tissue which makes up the
epithelium (skin) of the onion.
4. Place the onion skin on a clean microscope slide. Use a toothpick to gently remove any
wrinkles from the onion epithelium.
5. Using an eyedropper, add a drop of water to the slide and then place a cover slip over the
onion and water.
6. Place the slide on the stage of your microscope. Using low power, focus on the cells you
wish to study. (You may have to move the slide. Adjust magnification with the coarse
adjustment knob. You may have to adjust the light using the diaphragm.)
Q.2. Describe the general shape and structure of the epidermal cells as seen on low power.
7. Switch to the medium power objective lens and focus on the cells.
Q.3. Describe any differences in the general shape and structure of the epidermal cells as
seen on medium power from low power.
8. Switch to the high power objective lens and use the fine adjustment knob to focus on the
cells.
Q.4. Describe the general shape and structure of the epidermal cells as seen on high power.
9. Remove the slide from the stage. Stain the onion cell with a small drop of iodine or
methylene blue using the whisking procedure.
10. Place the stained onion cells back on the microscope stage and focus on the cells on low,
then medium and finally high power.
Q. 5. Describe how the stain has changed the appearance of the cells?
Q. 6. What is the size of one onion epidermal cell (high power). (Show your work)
11. Prepare a formal biological drawing of 3-4 onion cells from the stained sample as viewed
under high power. Label the cell wall, cell membrane, nucleus and cytoplasm on one cell.
12. Throw away the onion material. Clean your slides.
Part B - Procedure:
13. Use a Q-tip to obtain cheek cells and rub them onto the slide as shown on the video.
Cover with a slide cover.
14. Examine a group of cells under low power.
Q. 7. Describe the shape and structure of the animal cells as viewed on low power.
15. Switch to the medium power objective lens and focus on the cells.
Q. 8. Describe the shape and structure of the animal cells as viewed on medium power.
16. Switch to the high power objective lens and focus on the cells using the fine focus only.
Q. 9. Describe the shape and structure of the animal cells as viewed on high power.
17. Remove the slide from the stage. Stain the animal cells with a small drop of iodine or
methylene blue.
18. View the stained cheek cell under low, medium and high power.
19. Prepare a formal biological drawing of 3-4 animal cells when viewed under any
magnification you choose. Label the cell membrane, cytoplasm and nucleus on one cell.
Q. 10. Describe the differences in appearance between the cheek cells and the onion cells
as viewed on the magnification you have chosen to draw. (Focus on the structures and
shape. Remember that the colour of the cells is a result of the stain used.)
Q. 11. a. Calculate the approximate size of one animal cell. (show your work).
b. How does the size of one animal (cheek) cell compare to the size of the onion (plant) cell.
Part C – Procedure:
20. Obtain another sample from a plant. Use a scalpel to slice a thin cross-section from your
sample and place it on a slide. Examine on low power, medium power and high power.
21. Prepare a formal biological drawing of 3-4 of the cells when viewed under the
magnification which allows you to see the most organelles. Label all the organelles that you
see.
Q. 12. Describe the differences in appearance between this plant cell and the onion cell.
Discussion Questions:
In your Discussion and Conclusion, include answers to these questions. Do not rewrite the
questions. Remember, your discussion is in paragraph format, therefore, do not number the
answers.
1. Why are all the cells you observed classified as eukaryotic cells?
2. Why does it appear that there is nothing in the center of the onion and the leaf cell?
3. What organelles are found in plant cells but not in animal cells?
4. What evidence did you see that the onion cell is a plant cell?
5. Why are there no chloroplasts in the onion cells when there were in the leaf cells?
6. Which light intensity was best to view the stained onion cell? Why?
7. What is the purpose of microscopic staining? Did it work?