Today we’ll start section two of Unit 4 discussing Passive transport, or the movement of materials from high concentration to low concentration without the use of energy. There are three types of Passive Transport, all of which are related:

1. Diffusion: Movement of ANY material from High to Low concentration
2. Facilitated Diffusion: Diffusion of large materials that requires a transport protein to move across a membrane.
3. Osmosis: Diffusion of water across a membrane. In your cells, osmosis is a type of facilitated diffusion because it requires Aquaporins to move the water across the cell membrane.

For more information on this process please watch, and take notes on, the video below. When you are finished, please complete Directions of Osmosis Table (PDF) & the Passive Transport Review Questions (PDF).