2. Osmosis and Diffusion

3. Semi-Permeable membrane – allows some things through and keeps other things out (Also called selectively permeable)

4. Diffusion is the movement of particles across a semi-permeable membrane

5. Particles move from an area of higher concentration to an area of lower concentration. Generally, smaller particles move this way, and larger particles cannot get through.

6. Osmosis is the diffusion of water

7. Osmosis and Diffusion are both forms of Passive Transport – they require NO ENERGY BrainPopPassive BrainPopPassive

8. In order for larger molecules to move through the membrane, or for particles to move from low to high concentration, energy is needed. This is called Active Transport.

9. Which way will the particles move?

11. What if they had to move the other way?

12. They would have to move by Active Transport and this would require energy