Name: ___________________________________________ Date: _____________ Period: _______
Observing Plant and Animal Cells
Background Information:
One of the first scientists to look at cells under a microscope was an English
scientist by the name of Robert Hooke. He viewed and described the
appearance of cork under the microscope and decided to name the tiny boxlike structures that he observed “cells” because they looked like the small
chambers where monks lived.
By the early part of the 19th century, it was accepted that all living things are composed of cells.
Cells come in a variety of shapes and sizes, and cells perform different functions. Although
cells may appear outwardly different, they resemble each other because they share common
structures. In this lab you will look at two types of cells, a human cheek cell and an onion cell
and see how they are similar and how they are different.
Prelab:
1. What is the purpose of the iodine and methylene blue in this lab?
2. What shape do you think the plant cells will be?
3. What organelles do you think you will be able to see in this lab?
4. What will the toothpick be used for?
5. Why is it important to get a thin layer of onion?
Materials:
Microscope
Dropper
2 clean slides
2 cover slips
Toothpick
Cheek cells
Onion cells
Iodine
Methylene blue
Paper towel
Onion Cell Procedure:
1. Set up your microscope.
2. Get a clean slide. Place a drop of water on the slide. Using one of the cut sections of
onions at your station, remove the single layer of epidermal cells from the onion (the
thinner the better) Place the layer of tissue on a slide and then add a small drop of
iodine to the slide. Place a cover-slip on the slide, slowly lowering it over the sample to
avoid creating air bubbles.
3. Place the slide on the stage and view the slide under the low power.
4. Observe the cells under 4x, 10x, and 40x. Sketch what you see at each power in the data
section in your lab notebook.
5. Once finished learn the slide and cover slips and leave them to dry
Cheek Cell Procedure:
1. Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and
skin.
2. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
3. Stir the end of the toothpick into the stain and throw the toothpick away.
Name: ___________________________________________ Date: _____________ Period: _______
4. Place a cover-slip onto the slide
6. Place the slide on the microscope. Use the Scanning/Low power/ 4x objective to focus,
look at the stained slide under the microscope. You probably will not see the cells at this
power. Sketch what you see in the data section of your lab notebook and place the
magnification next to the drawing.
7. Switch to 10x power. Cells should be visible, but they will be small and look like blobs.
Solid dark objects are probably not cellular. Sketch what you see in the data section in
your lab notebook.
8. Once you think you have located a cell, switch to a high power (40x) and refocus using
the fine focus. Sketch what you seen in the data section of your lab notebook.
9. Once finished learn the slide and cover slips and leave them to dry.
Data:
Onion Cells:
Scanning (4x)
Low (10x)
High (40x)
Name: ___________________________________________ Date: _____________ Period: _______
Cheek Cells:
Scanning (4x)
Low (10x)
High (40x)
Name: ___________________________________________ Date: _____________ Period: _______
The light microscope used in this lab is not powerful enough to view other organelles in the cheek cell. Fill
out the table below to show what we could and could not see through our microscope.
Onion Cells
What organelles could be seen?
What organelles could not be seen?
What organelles could be seen?
Cheek Cells
What organelles could not be seen?
Post lab Questions:
Answer the following questions in complete sentences
1.
2.
3.
4.
5.
What type of cell did the cheek cell represent? What about the onion cell?
How does the shape of the onion cells differ from that of the cheek cells?
Which cells seem to be arranged in a more regular pattern?
What structures were you able to see in both types of cells?
Both plant cells and animal cells contain mitochondrion and yet there were not visible in
the cells you viewed in this lab. Does this mean that these organelles are not found in
cheek and onion cells? Why or why not? Explain your reasoning.
6. In class and in your reading you learned that one difference between plant and animal
cells is that plant cells contain chloroplasts. Were any chloroplasts visible in the onion
cells? Why or why not? Explain your reasoning.