Lab # _______
Name _________________________
Period/ pod # ______________
Date due__________
What structures are common to cells?
Introduction
The cell theory states that most living things are composed of units called cells. The
microscope reveals that cells are composed to tiny structures called organelles. Although
plant and animal cells have many of the same organelles, plant cells have certain organelles
that distinguish them fro the cells of animals and animal like protests. All plant cells have a
cell wall and all green plant cells have chloroplasts. Animal cells have neither a cell wall nor
chloroplasts; in other respects, however, the organelles of animal cells are similar to those of
plant cells.
Procedure:
1. Using the thin membrane from the inside surface of the onion.
2. Prepare a wet mount slide using iodine as the stain.
3. Focus the specimen in low power, draw what you see.
4. Change the objective to high power, focus, draw what you see.
5. Locate the nucleus and cell wall – label in your drawing.
6. Clean your slide.
7. Prepare animal cell slide
8. Place a small drop of iodine solution in the middle of a clean slide. With the flat end of a
toothpick GENTLY scrape the inside of one of you cheeks. This will remove some of
the cells that line the inside or the cheek.
9. Dip the end of the toothpick in the drop of iodine solution on the slide. Twist and stir
the toothpick in the solution in order to detach the scraped tissue from the toothpick.
10. Apply a cover slip and examine the specimen under the low power objective of the
microscope.
11. Draw what you see (using a good area of the specimen)
12. Switch to high power – draw what you see.
Directions:
In your lab notebook, please write down the following information as well as leave room for
the answers to each.
1. Purpose: What is the purpose?
a. What skills are you hoping to develop, what are you trying to learn?
b. What is a general summary of the procedure?
2. Hypothesis:
a. What comparisons do you expect to see?
b. What background information, previous knowledge, or research makes you
think this will happen?
3. Observations
1. …
2. …
3. …
4. Data:
Titled and labeled drawings on microscope pages
5. Questions:
1. Which organelles can you identify?
2. What is the advantage to staining cells?
2. In what ways do animal cells resemble plant cells?
3. In what ways do animal cells differ from plant cells?
4. What is the function of human cheek lining cells?
5. How are cheek epithelial cells adapted to their function?
6. Which cell appeared larger, the plant cell or the animal cells?
7. What cell part did you observe around onion cells that you did not see around
cheek cells?
8. Cheek cells often appear folded over, while onion cells don’t. Give one reason
why this is true.
9. Why is it difficult to see the cell membrane in onion cells?
10. The onion cells appear to have two dimensions – length and width. With the
help of your microscope, how can you determine whether it also has thickness?
11. Which organelle usually present in plant cells is absent from the cells of the
onion skin
6. Conclusion:
a) What comparisons did you expect?
b) What did you learn? Did the observations you expect to happen actually occur?

How do you know that?

What drawing(s) tells you that?
c) Conclusive statement?
d) Suggestions for improvement?

What were possible sources of error?
e) Suggestions for further research?

What other investigations could you do based on this?

What additional data needs to be collected to further support your findings?

Any questions that came up during the experiment that you would need to
investigate further?