Elodea Lab with Cytoplasmic Streaming and Plasmolysis

SCCS Honors Biology Name ______Period ______Date:______

Elodea Lab Purpose: We will use compound light microscopes to examine the presence of chloroplasts, cell walls, and cell membranes of the common aquarium plants, Elodea. You will also look at what happens when these cells are subjected to salt water and observe the process of plasmolysis, shrinkage of the cell contents due to water loss.

Materials:  Compound Light Microscope  Glass slides  Cover slips  Elodea plants  Tap Water  10% salt water

Procedures – Part 1: Elodea in water: 1. Get a wet mount slide of an Elodea Leaf from your teacher. 2. Observe the leaf at 40x and carefully draw what you see in the space marked Diagram #1. 3. Increase the magnification to 100x and refocus the slide using the fine knob. 4. Switch to high power magnification, 400x, and use the fine focus to bring the Elodea cells into sharp focus. Sketch what you see in the space marked Diagram #2. Label the total magnification you used. Label the following cell parts in Diagram #2:  Cell wall  Cell membrane (label where it should be)  Cytoplasm  Chloroplasts

Part 2: Elodea in water 10% Salt Solution: 5. Remove the slide from the stage of the microscope. 6. Carefully place 2 drops of the 10% salt solution on the slide at the left at the left edge of the cover slip 7. Tear off a small piece of paper towel and place the torn edge on the slide at the right edge of the cover slip. The piece of towel should begin to soak up water, drawing the salt solution under the cover slip. 8. Return the slide to the microscope stage and observe the cells at 40x, 100x, and 400x. Draw what you see at 400x in Diagram #3.

Flushing out the salt solution: 9. Remove the slide from the stage of the microscope 10.Place 3 - 5 drops of tap water on the slide at the cover slip. 11.Draw the water through using a small piece of paper towel. 12.Observe the cells at 40x, 100x, and 400x. What do you see happening? p. 2 of 3 Data:  Make your drawings as accurate as possible  Label neatly using a ruler  All labels need to be parallel to each other  Check your spelling

Diagram #1 Diagram #2 Total Magnification: ______Total Magnification: ______(Show your calculations) (Show your calculations)

Part 2: Plasmolysis

Diagram #3 Total Magnification: ______(Show your calculations) p. 3 of 3 Analysis and Conclusion: Part 1 1. What is the shape of a typical Elodea cell?

2. What are the green structures called and what is their function?

3. What is the function of the cell wall and how do you think the structure of the cell wall allows it to do its job?

Part 2 4. What happens to the cells as the salt water flows under the cover slip? What happens to the water in the vacuole in the cell?

5. Why didn’t the outer boundary of the cell collapse?

6. What happens to the cells when the salt water is flushed out with tap water?