B1- cell biology (diffusion and osmosis)

B1- cell biology

diffusion & osmosis

Diffusion- the spreading out of particles from an area of higher concentration to an area of lower concentration 

Diffusion happens in solutions and gases as the particles in these substances can move about freely and randomly

The bigger the concentration gradient, the faster the diffusion rate. A higher temperature will also increase diffusion rate as particles have more energy.

Cell membranes

• Hold cell toegther, let stuff in and out
• Dissolved substances can move in and out of cells by diffusion
• Only very small molecules can diffuse through cell membrane e.g. oxygen, glucose, amino acids and water
• Big molecules e.g. starch and protein…