OSMOSIS ACTIVITY
Recall Prior Knowledge:
1. Diffusion is the movement of a substance from an area of higher
concentration to an area of lower concentration
2. Diffusion requires a concentration gradient
3. Diffusion requires no energy input
4. Diffusion occurs due to the random motion of molecules
HOW DO CELLS REGULATE THEIR WATER CONTENT?
Activity 1:
Demonstration
Materials:
2 Potato slices
Hypotonic solution
Hypertonic solution (5% NaCl)
1.
2.
3.
4.
Place one potato slice in hypertonic solution
Place other potato slice in hypotonic solution
Have students make predictions & share
After some time have students feel potatoes
Discussion:
1. How did the potato in the hypertonic solution feel?
2. Why do you think it felt this way?
3. Did water move into potato cells or out of potato cells?
4. In terms of high and low concentration of water, what direction did water
move?
5. Did it move through a selectively permeable membrane?
6. How did the potato feel in the hypotonic solution feel?
7. Did water move into potato cells or out of potato cells?
8. In terms of high and low concentration of water, what direction did water
move?
9. What makes a solution hypertonic?
10. What makes a solution hypotonic?
Activity 2:
Animation
View the following animation and answer questions below:
http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS03/LS03.ht
ml
1. Does the hypotonic solution have more or less solute concentration than the
cells?
2. Does the hypotonic solution have more or less water concentration than the
cells?
3. Which direction does water move in a hypotonic solution, into cell or out of
cell?
4. Does the hypertonic solution have more or less solute concentration than the
cells?
5. Does the hypertonic solution have more or less water concentration than the
cells?
6. Which direction does water move in a hypertonic solution, into cell or out of
cell?
7. In an isotonic solution, what is the concentration of solutes and water
compared to the inside of cell?
8. Which direction does water move in a isotonic solution?
9. What is the difference in how a plant cell responds and how an cell responds
when placed in a hypertonic or hypotonic solution?
10. What environment is best for an animal cell?
11. What environment is best for a plant cell?
12. Will the animal cell burst if too much water enters cell?
13. Will the plant cell burst if too much water enters cell?
14. Will the animal cell shrivel if too much water leaves cell?
15. Will the plant cell shrivel if too much water leaves cell?
16. What determines how much water enters or leaves a cell?
Class Discussion
Activity 3:
Osmosis Problem:
Sequence for solving U-tube problem
1. Initially, which side is hypotonic?
2. Which side will water level raise?
3. Which side will have a greater number of glucose molecules after equilibrium
has been reached?
4. Which side will have a higher concentration of glucose after equilibrium has
been reached?
5. During the course of the experiment there will be a decrease in the
concentration of NaCl on which side?
Class discussion:
Activity 4:
Fill in class notes
Activity 5:
Check for understanding:
Dispense quiz questions
Discussion