1. Review the Plasmolysis
Plasmolysis is the shrinkage of the cell contents due to the water loss when a drop of salt water is added to the red onion / Elodea slide. The water molecules move out of the cell membrane causing the cell membrane and its contents to shrink into a blob in the center of wall

2. Plasmolysis: Red Onion
Red Onion Distilled Water
Red Onion Salt Water

3. Plasmolysis: Elodea
Elodea : Distilled Water
Elodea: Salt Water

4. Plasmolysis: Questions
1. Does the distilled water or salt water cause Elodea cells to decrease in size? Why do the cells shrink? 2. Why didn’t the salt from the outside just move inside the cell instead of the water moving out of the cell? What does this tell you about the cell membrane? 3. What structure did the shrinking of the cell allow you to observe? 4. Why didn’t the cell wall shrink? 5. Do you think it would be possible for Elodea to go back to their original condition after shrinking ? Why?

5. Answers
1. Does the distilled water or salt water cause Elodea cells to decrease in size? Yes
Why do the cells shrink?
Higher salt concentration caused the diffusion of more water from within the cell to outside the cell.
2. Why didn’t the salt from the outside just move inside the cell instead of the water moving out of the cell?
The cell membrane is selectively permeable.
What does this tell you about the cell membrane?
It allows the movement of water but not salt

6. Answers continue
3. What structure did the shrinking of the cell allow you to observe? cell wall 4. Why didn’t the cell wall shrink? It is rigid and provides support to the Elodea plant cell. Also, it allows salt to go through so it does not shrink, unlike the cell membrane. 5. Do you think it would be possible for Elodea to go back to their original condition after shrinking? Yes Why? When concentration changed- deplasmolysis would occur.