1. Cellular Processes
Diffusion and Osmosis

2. Concentration (p.16)
Concentration: the number of molecules of a substance in a given volume
Low Concentration High Concentration
- Think of Juice from concentrate : you have to add water. This is really concentrated fruit juice that needs to have water added to it to make it lower in concentration

3. Diffusion (p.16)
Diffusion is the movement of particles from an area of high concentration to low concentration until all the particles are evenly distributed
Watch DEMO. (food colour in 3 beakers)
How does diffusion affect the size of a cell?

4. Why is diffusion important?
Diffusion is an essential cell process. It is responsible for moving things around in cells. It occurs:
Within a cell: movement of substances from one organelle to another
Across a cell membrane: oxygen diffuses through cell membranes into cells, carbon dioxide waste diffuses back out.
Outside a cell in body fluids: nerve cells communicate with each other by releasing chemicals which diffuse between the spaces between cells

5. Osmosis (p.17) Osmosis is the movement of water molecules
across a semi-permeable membrane in response to concentration differences.
Semi-permeable membranei

6. Osmosis
45 sec.
Water Salt + Water

7. Osmosis
2min

8. Egg in corn syrup then water (4min)

9. Diffusion explained (39 sec)
example (40 sec)