Diffusion - Biology Revision
KEY FACTS ABOUT DIFFUSION:
- Diffusion is the spreading out of particles from an area of high concentration to an area of low concentration.
- Diffusion happens in both solutions and gases - thats because the particles in these substances are free to move about randomly.
- Dissolved substances can move in and out of cells by diffusion.
- Only very small molecules can diffuse through cell membranes though - things like oxygen, glucose, amino acids and water.
- Big molecules like strach and proteins can't fit through the membrane.
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