B6 - microscopic life in water

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  • Created by: Naomi
  • Created on: 21-01-13 15:15
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  • Microscopic life in water
    • Advantages of living in water
      • Temperature of water does not change as much as the air temperature
      • Dehydration is unlikely to happen
      • Water supports their weight
      • Organisms can grow much bigger
      • Excreted waste is diluted in the water
    • Organisms such as an amoeba have a contractile vacuole that can store any excess water
      • The vacuole can then fuse with the cell membrane and empty the water to the outside
    • Disadvantages of living in water
      • In salt water too much water could be lost
      • Too much water could get in and burst the cells
        • In freshwater organisms can take up too much water by osmosis. In salt water, too much water may be lost to the surroundings by osmosis
          • In salt water too much water could be lost
      • Difficult to swim against the current
      • Advantages of living in water
        • Temperature of water does not change as much as the air temperature
        • Dehydration is unlikely to happen
        • Water supports their weight
        • Organisms can grow much bigger
        • Excreted waste is diluted in the water
    • Plankton
      • Phytoplankton are plants and they photosynthesise
      • Zooplankton are microscopic animals
        • Baby fish are zooplankton
      • The numbers of phytoplankton and zooplankton vary at different depths and in defferent seasons
        • This is because phytoplankton needs light so it can photosynthesise
    • Food webs in the ocean
      • Most rely directly on green plants or phytoplankton
        • Called a grazing food web
      • Others deeper in the ocean feed on marine snow
        • Marine snow is organic matter that falls from the surface, including dead and dying matter and faeces
      • Some rely on bacteria, deep in the ocean, acting as producers
        • Some bacteria can use hydrogen sulphide to make organic food, this means food webs can exist where there is no light
    • Water pollution
      • Eutrophication
      • Some species are more sensitive to pollution than others and so they can be used as bioligical indicators for pH and oxygen
  • Disadvantages of living in water
    • Too much water could get in and burst the cells
      • In freshwater organisms can take up too much water by osmosis. In salt water, too much water may be lost to the surroundings by osmosis
      • Difficult to swim against the current

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