Diffusion is the movement of molecules from a high concentration to a low concentration. • Many molecules diffuse across cell membranes
Molecules of oxygen are represented by the small circles on the diagram to the left. • Which way will oxygen diffuse in this example?
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?
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.
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?
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.
In this example there is more salt in the blood than in body cells.. • Which way will water move in this example?
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?
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?