diffusion

• Diffusion

  • the movement of particles from where there are lots of them to where there are fewer
  • higher concentration -> lower concentration
  • higher temperature means a faster diffusion rate
• Cell membranes

  • allow particles to diffuse in and out of a cell
  • only small molecules can fit- e.g. oxygen, glucose, amino acids and water
  • big particles like starch and proteins can’t fit through
  • molecules flow through the membrane from a higher concentration to an area of lower concentration
  • the larger the surface area of the membrane, the faster the diffusion rate
• Osmosis

  • the movement of water molecules across a partially permeable membrane from a less concentrated solution to a more concentrated solution
  • partially permeable membrane- has very small holes in it
  • tiny molecules (like water) can pass through it but bigger molecules (like sucrose) can’t
  • less concentrated solution -> more concentrated solution