Living Cells Lab
Answers in complete sentences:
1.
Onion Epidermis Cell
100x
unstained
Onion Cell – High Power
Answers in complete sentences:
2.
Label:
1
Elodea Cell – High Power
Answers in complete sentences:
3.
4.
5.
6.
7.
Label:
Onion cell
Human Epidermal Cell – High Power
Elodea cell
Answers in complete sentences:
8.
9.
Plant cell
10.
Label:
11.
2
Animal cell
LIVING CELLS LAB
PURPOSE:



To practice microscope focusing skills.
To identify important structures in plant and animal cells (onion, elodea, and human epidermal cells).
To make inferences about the functions of plant and animal cell structures.
MATERIALS:
onion
elodea
microscope slides and cover slips
droppers
tape
iodine solution
methylene blue solution
PROCEDURE:
ONION
A. Obtain a small piece of the epidermis on the inner surface of the onion (concave side).
B. Prepare a wet mount of the onion epidermis as follows:
 Place the onion epidermis on the slide and smooth out any wrinkles.
 Add 1 or 2 drops of water.
 Put on the cover slip. (Be sure the water comes to its edges, but not beyond.)
C. Examine the onion epidermis under low power of your microscope. Look for cell boundaries.
Then, switch to medium power.
Draw: a small part of the field of view (3 cells) to show the shapes and arrangements of the cells.
Label: cell wall/cell membrane, nucleus (if visible), and cytoplasm.
Answer: 1. What is the general shape of the onion cells?
D. Remove the slide from the microscope stage. Place a drop of iodine stain along one edge of the
cover slip. Draw the stain under the cover slip by touching a piece of paper towel to the opposite
edge (Figure 1). CAUTION: Stains can cause permanent damage to clothes and laboratory
surfaces. Handle carefully.
Figure 1.
E. Place the slide on the microscope stage. Focus in low power. Then, switch to medium and high
power. In high power, slowly rotate the fine focus knob and notice that different parts of the cell
will focus at different times. This shows you that cells have depth.
Draw: one onion cell. Include as much detail as you can see.
Label: cell wall/cell membrane, nucleus (circular structure stained brown), and cytoplasm.
Answer: 2. What is the shape of the nucleus?
3
ELODEA
F. Elodea (sometimes called Anacharis) is a common flowering plant that lives in fresh water. The
green cells of elodea are similar in structure and function to those found in other plants.
Take one leaf, and place the leaf with its underside up on the slide. Add 1 drop of water and put
on a cover slip.
G. Observe the leaf under low power. Then, switch to medium power. By slowly turning the fine
adjustment knob back and forth, determine the number of cell layers in the leaf.
Answer: 3. How many cell layers are present in the leaf?
H. Switch to high power. Select an “average” cell and focus on it carefully.
Draw: one elodea cell. Include as much detail as you can see.
Label: cell wall/cell membrane, chloroplasts, vacuole, and cytoplasm.
Answer: 4. What is the evidence that the cell is living?
I. Some elodea cells are packed with small green circular structures. These structures are called
CHLOROPLASTS. If you look carefully, you may see some chloroplasts gliding along the
edges of the cell.
Answer:
5. The part of the onion from which you took cells is usually found below ground. The
elodea plant is found where sunlight strikes the plant. What does this suggest about the function of
chloroplasts?
6. Where are chloroplasts mainly located in the cell? Why?
7. Compare and contrast the two kinds of living cells you have seen in the Venn diagram. How
are they alike? How are they different?
HUMAN EPIDERMAL CELLS
J. Wash the underside of a wrist that will be sampled for epidermal cells with soap and water. After
drying, stick a clean piece of clear tape on the underside of the washed wrist. Gently remove the
piece of tape from the wrist being careful to avoid getting fingerprints on the tape.
K. Place the tape, sticky-side up, on a clean microscope slide. Add 2-3 drops of methylene blue stain.
Gently place a cover slip on the sticky tape. Observe under low power. Then, switch to medium
power. You may find that some of the cells are folded over or piled on top of one another. Some
may be broken. Find one or two that you can see clearly. Center these for viewing.
Answer: 8. What is the general shape of an epidermal cell? How does the edge of this kind of cell
compare with the plant cells you observed?
L. Switch to high power and find an average epidermal cell with a nucleus.
Draw: one epidermal cell. Include as much detail as you can see.
Label: cell membrane, nucleus, and cytoplasm.
Answer:
9. How are the plant and animal cells you have seen alike?
10. Would you expect cells from other parts of your body to be exactly like the cells from your
skin? Why or why not?
11. An organism may have many small cells rather than a few large cells. Suggest one or more
possible explanations for this.
4