diffusion

• diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration, it happens when particles are free to move around (solutions and gasses).

  the bigger the concentration gradient (difference in concentration) or the higher the temprature the faster the diffusion rate.
• cell membrains let small molecules (e.g oxygen, glucose, amino acids and water) move in and out cells by diffusion and while stopping bigger molecules (e.g. proteins).

  particles flow through the cell membrane from a higher concentration to a lower concentration,

  the larger the surface area the faster the rate of diffusion (more particles can pass through at once).