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.