B2 - diffusion

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  • Created by: Charlotte
  • Created on: 08-04-13 17:06
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  • Diffusion
    • Molecules in gases and liquids move around randomly because of the energy they have
    • Diffusion is the spreading out of the particles of a gas, or of any substance in solution
    • Because the particles move randomly, there will be a net(overall) movement from an area of high concentration to an area of lower concentration
    • The net movement into or out of the cells depends on the concentration of the particles on each side of the cell membrane
    • The difference in concentration is called the concentration gradient
    • The larger the difference in concentration, the faster the rate of diffusion
    • Examples of diffusion:
      • the diffusion of oxygen into the cells of the body from the bloodstream as the cells are respiring (and using up oxygen)
      • the diffusion of carbon dioxide into actively photosynthesising plant cells
      • the diffusion of simples sugars and amino acids from the gut through cell membranes


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