B4 - Decay

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  • Created by: Naomi
  • Created on: 20-01-13 17:55
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  • Decay
    • Earthworms and maggots are called DETRITIVORES because they feed on dead and decaying material (detritus)
      • Detritivores increase the rate of decay by breaking up the detritus and so increasing the surface area for further microbial breakdown
    • The rate of decay can be increased by increasing the temperature, amount of oxygen and water
      • Increasing the temperature to an optimum of 37 for bacteria and 25 for fungi will increase their rate of respiration, higher temperatures will denature enzymes
      • By increasing the amount of oxygen, bacteria will use aerobic respiration to grow and reproduce faster
      • Increasing the amount of water will allow for material to be digested and absorbed more efficiently and increase growth and reproduction of bacteria and fungi
    • A SAPROPHYTE for example a fungus, is an organism that feeds on dead and decaying material
      • Fungi produce enzymes to digest food outside their cells and then reabsorb the simple soulable substances
        • This type of digestion is called extracellular digestion
    • Food preservation methods reduce the rate of decay
      • In canning, foods are heated to kill bacteria and then sealed in a vacuum to prevent entry of oxygen and bacteria
      • Cooling foods will slow down bacterial and fungal growth and reproduction
      • Freezing foods will kill some bacteria and fungi and slow down their growth and reproduction
      • Drying foods removes water so bacteria and fungus cannot grow
      • Adding salt or sugar will kill some bacteria and fungi as the high osmotic concentration will remove water from them
      • Adding vinegar will produce very acidic conditions killing most bacteria and fungi


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