Download Part A

Cell Lab
Part A. The Cell Wall
Cork cells are excellent for studying a cell part common to all plant cells. That part is the cell wall. It
is the only cell part remaining in a cork cell; therefore, it is easily visible.
Obtain a prepared slide of cork.

Examine the cork slide under scan and low power only. If you use high power you run the risk
of breaking the slide. Be very careful. Use the fine adjustment to obtain a three-dimensional
view of the cells.

Use the space below to draw several cork cells as they appear under the low magnification
Label the cell wall.
1. What name is given to the small units making up cork and all living things? _________________
2. Describe the appearance of these units in cork. _______________________________________
3. Are cork cells alive? _________
4. Are the cells filled with living material or are they empty? ____________________
5. What specific cell part is all that remains of the cell? _________________________________
6. In 1665, Robert Hooke, an English scientist, reported an interesting observation while looking
through his microscope at cork. “I took a good clear piece of cork, and with a penknife sharpened
as keen as a razor, I cut a piece of it off, then examining it with a microscope, me thought I could
perceive it to appear a little porous, much like a honeycomb, but that the pores were not regular.”
a. What were the honeycomb units at which Hooke was looking? _______________________
b. What specific cell part was all that was left of cork? _______________________________
c. What carbohydrate makes up this part? __________________________________
d. Are cork cells part of a producer or a consumer? __________________________
Part B. Cell Membrane and Cytoplasm
Human cheek cells are excellent for examining cell membranes (the outer covering) and cytoplasm
(cell contents).

Place a drop of iodine solution onto a slide.

Gently scrape the inside of your cheek with the end of a toothpick. You will not be able to see
anything on the toothpick when you remove it from your mouth.

Dip the toothpick into the iodine on the slide and mix once or twice.

Add a cover slip and examine under low and high power of your microscope.

Locate and examine cells that are separated from one another rather than those that are in
clumps.

Use the space below to draw several cheek cells as they appear under high magnification
Label the cell membrane and cytoplasm.
1. Describe the shape of cheek cells. ________________________________________________
2. Do cheek cells have cell walls? _____________
3. Do cheek cells have cell membranes? _______________
4. Why might the shape of cheek cells be less regular than the shape of cork cells? ____________
__________________________________________________________________________
5. Describe the appearance or texture of cytoplasm. _____________________________________
6. Are cheek cells alive? __________
7. Do cheek cells come from consumers or producers? ________________________________
8. Why was iodine solution added to the cheek cells? ____________________________________
Part C. Cell Nucleus and Nucleolus
Onion bulb cells can be used to observe the cellular structures called the nucleus and nucleolus.

Remove the almost transparent layer of cells between the rings of the onion. Place this layer
onto a microscope slide.

Add a drop of water to the slide. Uncurl or unfold any overlapped portion of the cell layer.
Make sure the layer is perfectly flat. Add a cover slip.

Observe the cells under low and high power of your microscope. Note the brick wall
appearance of the cells with cell walls separating the cells.

Attempt to locate a small round structure, the nucleus, within each cell.

Stain the cells with iodine stain.

Now locate a nucleus. Examine a nucleus carefully by using the three-dimensional technique.

With high power, observe the tiny dot or eye-like structures within the nucleus. These are
nucleoli.

Diagram and in the space provided what you observe under high power. Label the cell
nucleus and nucleolus
1. Is cytoplasm visible in onion cells? __________
2. Can you see the cell membrane? ____________
3. How many nucleoli are in each nucleus? _______________
4. Why were the cells stained? _______________________________________________________
5. Other than the nucleoplasm and nucleoli, what is found in a nucleus? ______________________
Why might you not be able to see these structures at this time? ________________________
6. What is believed to be the function of the nucleoli? _____________________________________
7. What structure separates the contents of the nucleus from the cytoplasm? __________________
Part D. The Flower Petal

Prepare a wet mount of a small piece of flower petal. Observe under low and high power
magnification.

Use the space below to draw several flower petal cells as they appear under high
magnification.
1. Is a flower a producer or consumer? ____________________________
2. Do petal cells have cell walls? ______________
3. Do petal cells have cytoplasm? _____________
Part E. Chloroplasts
Another organelle found in the cells of most producers is the green chloroplast. Elodea, a common
water plant, is good for observing these important structures.

Prepare a wet mount of an elodea leaflet.

Using low power of your microscope, position you slide so you are looking near the edge of the
leaflet. Locate green, oblong cells. Examine these cells under high power.

Note the small green organelles inside each cell. These are chloroplasts. Movement of the
chloroplast within the cell can often be observed. Attempt to locate moving chloroplasts.

Observing one cell for several minutes is sometimes needed in order to see cytoplasmic
streaming (movement). Light from the scope will warm the cell and help to induce movement.

Now take your slide and stain the elodea with iodine stain. Locate a spike cell along the edge
of the leaflet.

Label in the space below an oblong cell and a spike cell as seen under high power.

Draw what you see in the space provided.
Oblong Cell
Spike Cell
1. Can you see nuclei in the spike cells? __________
2. In what part of a cell are chloroplasts embedded? ___________________________________
3. Do elodea cells contain nuclei? ____________
4. Do elodea cells have cell walls? ____________
5. What makes chloroplasts green? _____________________________
6. An elodea leaf appears uniformly green to the eye. Is the green color distributed evenly
throughout the cell or is it only in specific organelles? _________________________________
7. Is elodea a producer or consumer? ___________________________
8. What is the function or role of chloroplasts? _________________________________________
9. Term referring to the cell movement - __________________________
Organelle responsible for this movement - ______________________________
10. In what direction is this movement? ___________________________________
Part F. Nongreen Plastids
Nongreen plastids that serve as food storage areas are visible in potato cells.

Use a razor blade to cut a very thin slice from a potato chunk. Do no use the peel. The slice
must be tissue-paper thin.

Prepare a wet mount of the slice. Observe the potato cells under low and high power of your
microscope. The cell wall of individual cells may be observed. However, the contents of these
cells will contain so many plastids that you will not be able to see any other organelles.
(Reduced light will aid in observing the cell wall.)

Add iodine stain. Observe the cells under low and high power.

Diagram and in the space below several potato cells under high power. Label the
leucoplasts.
1. Is potato a consumer or producer? ____________________________
2. What might be the chemical nature of the substance in plastids? (Use the color after the addition
of iodine as a clue.) ______________________________________________________________
3. Are nongreen plastids capable of directly manufacturing the chemical substance found there? ___
4. Name of these plastids - ____________________________
Function of this type of plastid - ________________________________________________
Comparison of Producer and Consumer Cells
Cell Type
Producer
Consumer
Cytoplasm
Nucleus
Cell Wall
Chloroplasts
Summary
1. What cell parts are found only in cells of producers? ____________________________________
2. Nonliving covering of a plant cell - __________________________
3. What advantage do producer cells have over consumer cells because of the chloroplasts?
_________________________________________________________________________
4. Why is it necessary for all cells to have a nucleus? _____________________________________
5. List at least three other organelles that are found in the cytoplasm of all cells.
1. _____________________________
2. _____________________________
3. _____________________________
6. Complete the drawing.
cell wall
cytoplasm
ribosome
It shows a typical plant cell. Label those parts listed below.
cell membrane
nucleus
endoplasmic reticulum
chloroplast
nucleolus
Golgi body
mitochondrion
vacuole
7. Complete the drawing. It shows a typical animal cell. Label those parts listed below.
cell membrane
nucleus
nucleolus
endoplasmic reticulum
mitochondrion
centriole
Golgi body
ribosome
lysosome
cytoplasm