Download Plant and Animal Cells- Lab file

Lincoln High School
AP Biology- Comparing Plant and Animal Cells Lab
Name: _________________________________
Background: Cells are the basic functional unit of all living organisms.
Plant and animal cells have different characteristics. Both plant and
animal cells occur unicellularly or within multi-cellular organisms.
Because they often take on special functions within tissues, animal cells
are frequently more specialized than plant cells. Epithelial (skin) and
blood cells are examples of different tissues. In this lab, you will look at
epithelial cells of both plants and animals. These cells are specialized for
transportation and protection. The individual cells of these layers may be
shaped like cubes, columns, or be flat, depending on their location and
function. Normally, we expect cells taken from a plant sample to be boxshaped and animal cells to be more spherical.
Purpose: The purpose of this laboratory investigation:
 to properly utilize how to use a microscope
 to visualize the differences between plant and animal cells
Materials:
 Compound Microscope
 Microscope Slides/Covers
 Iodine Solution
 Methylene Blue Stain
 Onion
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Tweezers
Single-edged razor
Paper towel
Flat edged toothpicks
Part I: Plant Cells- Procedure:
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Obtain a piece of onion and
remove a small square from
it.
Use tweezers to pull away the
epidermis from the inner surface. Be careful not to wrinkle the
membrane. Place a drop of water on the center of the microscope
slide. Add a piece of membrane about 0.5cm2 with a scalpel.
Use a flat toothpick to straighten out any wrinkles. Take a cover
slip and place it on top of the onion membrane- lowering it at an
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angle to the slide to avoid any air being trapped underneath. (WET
MOUNT)
Place one drop of Iodine Stain at the very edge of the slide. Allow
this stain to mix with the water and stain the onion cells. After a
minute, use tissue or paper towel to absorb extra fluid from the
opposite slide of the coverslip.
Examine the epidermis first under the low power objective of your
microscope. If the specimen is still difficult to see try reducing
the illumination by adjusting the diaphragm of the microscope.
Then examine it under high power.

Record your observations below.
Data:
Part III: Animal Cells- Procedure:
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Prepare a slide of epithelial cells
from your oral cavity, by the
following procedure.
Take a flat toothpick (a NEW one) and using the large end, scrape
the inside of your cheek 3 or 4 times.
Gently make a smear in the center of the slide- about the size of a
dime.
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Carefully place 1 drop of Methylene Blue Stain on the center of
the stain. Place a cover slip over the drop of the stain. Allow this
slide to sit for about 5 minutes.
Using a paper towel or tissue, blot the edge of the coverslip to
absorb any excess fluids.
Examine the cells, first under middle power, then under high
power. At first, the field of view will be light blue and the cells will
be slightly darker blue. After a few minutes, the field will lighten
and the cells will become slightly purple.
Record your observations below. Label the organelles that you see.
Analysis/Conclusion: (Answer using FULL sentences)
1: How many layers thick is the epidermis of an onion?
2: What is the general shape of the plant cell? Animal cell?
3: What does the nucleus look like under middle power? High power?
4. Describe the shape and the location of chloroplasts.
5. Why were no chloroplasts found in the onion cells? (hint: think about where
you find onions)
6. Which type of cell was smaller – the onion cells or the elodea cells?
7. Summarize what you learned by doing this lab (2-3 paragraphs)
Part II: Elodea Cells
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Obtain a piece of Elodea and
remove a small leaf from it.
Place a drop of water on the
center of the microscope slide.
Use a flat toothpick to straighten out any wrinkles. Take a cover
slip and place it on top of the Elodea- lowering it at an angle to the
slide to avoid any air being trapped underneath. (WET MOUNT)
Examine the leaf under high power objective of your microscope.
If the specimen is still difficult to see try reducing the illumination
by adjusting the diaphragm of the microscope.

Record your observations below.
Label:
 Cell Wall
 Nucleus
 Cytoplasm
1.
What
is
the
function of chloroplasts?
2. Name two structures found in plant cells but not animal cells.
3. Name three structures found in plant cells AND animal cells.
4. What structure surrounds the cell membrane (in plants) and gives the
cell support.
Fill out the Venn Diagram below to show the differences and similarities
between the onion cells and the elodea cells.