Biology B2 Notes- Diffusion

Diffusion is the random movement of particles in a fluid from an area of high concentration to an area of low concentration until there is no net movement or equilibrium has been achieved.

The larger the difference in concentration, the faster the diffusion rate.

An instance of this in organic being is in cells. Whilst the cell membrane may hold a cell together, it also allows only certain dissolved substances into and out of the cell by means of diffusion. Only small molecules can diffuse into the cell however (examples being oxygen, glucose, amino acids and water). Larger molecules like starch and protein cannot fit through the membrane.