3.7 Ecology

  • Created by: 14mut64
  • Created on: 11-05-19 21:49


  • Species - organisms that are able to interbreed to produce fertile offsprings
  • Habitat - the place where an organsim lives
  • Population - all the organisms of one species in a habitat
  • Community - all the different species in the habitat
  • Ecosystem - all organisms living in a particular area and all the abiotic conditions
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Abiotic factors affecting Communities

  • Environmental conditions
    • the abundance and distribution of organisms can be altered by temperature; light intensity (plants only); moisture level; and soil pH
    • e.g. the distribution of a bird species is changing in Germany because of a rise in average temperature
  • Toxic chemicals
    • e.g. chemical pesticides and fertilisers
    • pesticides can build up in food chains through bioaccumilation
    • bioaccumilation is where at each stage of the food chain, the concentration of the pestcide increases, so organisms at the top of the food chain, receive a toxic overdose.
    • excess fertilisers released into rivers and lakes can cause eutrophication, which leads to death of organisms
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Biotic factors affecting Communities

  • Availability of food
    • e.g. in a bumper year for berries, the population of blackbirds increase because there is enough food for all of them, so they are more likely to survive and reproduce.
  • Number of predators
    • e.g. if the number of lions decreases, then the number of gazelles might increase, as there are fewer of them that will be eaten by the lions
  • Competition 
    • organisms compete with other species (and members of their own species) for the same resources
    • e.g. plants need things like light, space, water and minerals from the soil. Animals compete for things like territory (space), shelter, food, water and mates
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