1. Diffusion and Osmosis Demonstration Miss McLellan and Mr. Wall

2. Review thus far: Talked about the different parts of the cell. Semi-permeability of cell membrane. Transportation of molecules in and out of the cell. Today, we will demonstrate the processes of diffusion and osmosis.

3. What is Diffusion?

4. Diffusion is…. the movement of particles from an area of high concentration to an area of low concentration.

5. What is Osmosis?

6. Osmosis is… The diffusion of water through a semi- permeable membrane. More specifically, it is the movement of water across a semi- permeable membrane from an area of high water potential to an area of low water potential.

7. Osmosis

8. Today… Lab demonstrating the processes of diffusion and osmosis.

9. Lab Write-up Must Include: Prediction Materials Used Procedure Post-lab analysis

10. Predictions? Answer prediction questions Make your prediction as to what you think will happen.

11. Key Terms: The cell membrane is selectively permeable, meaning that some substances can pass across them and others cannot.

12. Key Terms: Hypertonic solution – contains a high concentration of solute relative to another solution. When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. Hypotonic solution- contains a low concentration of solute relative to another solution. When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode.

14. Key Terms (cont’d): Indicator – a substance that indicates the presence or concentration of a certain constituent. Iodine solution is used to test for starch. A dark blue colour indicates the presence of starch.

15. Key Terms (cont’d): Indicator – a substance that indicates the presence or concentration of a certain constituent. Iodine solution is used to test for starch. A dark blue colour indicates the presence of starch.

16. Data Table Starting ColourColour After 15 minutes Solution in Container Solution in Bag

17. Explanation: Cell membrane performs like a window screen. Air and microscopic particles can flow in but large objects like insects are kept out. The cell membrane is a selective in allowing molecules to pass in and out and is therefore is semi-permeable.