GCSE Biology Unit 2 (3)

Diffusion

• Diffusion is a simple process.
• It's just the gradual movement of particles from an area where there's a lot of them to places where there are fewer of them.
• It is just the natural tendency for stuff to spread out.
• The actual definition is:
• Diffusion is the passive movement of particles from an area of high concentration to an area of low concentration.
• Diffusion happens in both liquids and gases - that's because the particles in both these substances are free to move about randomly.
• The simplest type is when different gases diffuse through each other.
• The bigger the concentration, the faster the rate of diffusion.
• Cell membranes are quite clever
• They are clever because they hold the cell together BUT they…