1. Diffusion is the movement of molecules from a high concentration to a low concentration.
Many molecules diffuse across cell membranes

2. Molecules of oxygen are represented by the small circles on the diagram to the left.
Which way will oxygen diffuse in this example?

3. The speed of diffusion depends on several factors, including temperature.
Do think a higher temperature will cause diffusion to occur more rapidly or more slowly?
What is your hypothesis?

4. 1. Fill a beaker or glass three fourths full with cold tap water.
2. Fill another beaker or glass with very hot water.
3. At the same time lower a tea bag into each of beakers or glasses. Do not mix.

5. Describe the rate of diffusion in the two.
Was your hypothesis correct?
What does this experiment tell you about how temperature affects the rate of diffusion?

6. Osmosis is the movement of water (red dots) through a semipermeable membrane to a higher concentration of solutes (blue dots).
Water easily moves through cell membranes by osmosis.

7. In this example there is more salt in the blood than in body cells..
Which way will water move in this example?

8. Will water move into or out of the fish?
A marine fish has about 1% salt in his body. The ocean water is 3.5%.
Will water move into or out of the fish?

9. Will water move into or out of the fish?
A freshwater fish has about 1% salt in his body. Freshwater is close to 0% salt.
Will water move into or out of the fish?