NAME:_______________________________________ PERIOD:_________________

 

PARTNER’S NAME:____________________________ DATE:___________________

 

THE STRUCTURE AND FUNCTION OF CELLS

 

PURPOSE:  To compare and contrast several types of plant cells with animal cells.

 

PROCEDURE:

1. Take one of the onion layers and turn it sideways with its concave surface toward you.  With your thumbs and forefingers, hold the piece of onion near its center and bend the piece sharply toward you so the shiny back surface snaps.  This will leave a thin membrane on the inner surface that can be peeled off easily with forceps. Make a wet mount slide with this small piece of membrane, making sure that is the membrane is not wrinkled. Place a drop of iodine on the onion before lowering the coverslip into place. Examine the onion cells under low power and then switch to high power.  Draw a diagram of the onion cells under high power and label the organelles listed.

 

2. Take a sprig of Elodea and pull off one of the smaller leaves near the tip of the spring with forceps.  Make a wet mount slide with the small leaf. Examine the Elodea cells under low power and then switch to high power.  Draw a diagram of the Elodea cells under high power and label the organelles listed.

 

3. Take flat-sided toothpick and GENTLY rub the inside of your cheek using an up-and-down motion. Remove the cells from the toothpick by swirling the end of the toothpick in a drop of water on the slide. THROW THE TOOTHPICK AWAY AFTER USE. Add a drop of methylene blue before lowering the coverslip into place. You will need to draw out some of the stain before looking for the cheek cells. See the diagram below. Place a piece of paper towel on one side of the cover slip and several drops of water on the other side of the cover slip. The stain should be absorbed by the paper towel. Examine the cheek cells under low power and then switch to high power. Draw a diagram of the cheek cells under high power and label the organelles listed.

Text Box: Water
Text Box: Paper towel

  

 

 

 

 

 

 


 

4. Clean all three glass slides and coverslips with water.  Be sure to dry them. Replace the cover on the microscope.

 

5.  Answer the laboratory questions.

 

 

OBSERVATONS:

Onion Cell :                                                                  Label the following:

                                                                                      Cell wall

                                                                                                                                                Nucleus             

                                                                                      Nucleolus

                                                                                      Cytoplasm

 

 

                                                                  

 

Mag: ______

 

 

Elodea Cell:                                                                 Label the following:

                                                                                      Cell wall

                                                                                                                                                Chloroplasts  

                                                                                      Cytoplasm

 

 

                                                                  

 

 

Mag: _____

 

 


 

Cheek Cell:                                                                  Label the following:

                                                                                      Cell membrane

                                                                                                                                                Nucleus

                                                                                                            Nucleolus

                                                                                      Cytoplasm

 

 

 

 

Mag: _____

                                                                  

 

QUESTIONS:

1. List two features that show onion cells are plant cells?

 

 

 

2. How are Elodea cells similar to onion cells?

 

 

 

3. How are Elodea cells different from onion cells (state the obvious)?

 

 

 

4. What is the purpose of chloroplasts?

 

 

 

5. Why are chloroplasts present in Elodea cells but not present in onion cells?

 

 

 

6. List two features that show cheek cells are animal cells (do not list what the cheek cells do NOT have)?

 

 

 

7. Are plant cells and animals cells prokaryotic or eukaryotic cells?

 

 

 

8. Explain your answer from question #7.

 

 

 

9.  Name at least three ways the animal cells are different from plant cells.

Plants

Animals

 

 

 

 

 

 

 

 

 

 

 

10.  “Plants and animals obtain food in different ways.” What microscopic evidence would you use to prove this statement?