• Created by: Sophiw
  • Created on: 06-12-12 10:03


  • dissolved particles (molecules and ions) move in and out of cells by diffusion, particles move from an area of high concentration to an area with a lower concentration down a concentration gradient
  • to get into cells particles must pass through cell membranes which only allow small molecules through, which is fine for co2 and oxygen
  • diffusion does not use energy because the particles move spontaneously
  • distance, concentration gradient and surface area affect the rates of diffusion
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  • osmosis is a special kind of diffusion is is diffusion of water
  • the membrane is passes through is called a partially permeable membrane
  • in plants when there is a lot of water there is high turgor pressure and when there is a lack of water the cell becomes flaccid, eventually they collapse and it becomes a plasmolysed cell
  • in animal cells alot of water may cause the cell to burst due to lack of cell wall, this is called lysis, when there is a lack of water the cell becomes crenated and wrinkles
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