organisms and their environment: distribution of organisms

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  • organisms and thier environment:distrubutiion of organisms
    • distribution may be affected by physical factors.
    • transects and quadrats collect quantitative data about organisms in their habitat.
      • mean , median and mode can then be found from this set of data.
      • usually not possible to count entire population of a particular organism in a habitat.
      • must be sampled instead.
      • transects
        • A line across a habitat or part of a habitat. can be string or rope. number of organisms of each species can be observed and recorded at several intervals throughout the transect.
      • Quadrats
        • a square mad of wire-usually.. may have more quares in centre to makk of smaller aread. anything unernath the quadrat can then be identified and counted.
          • should be placed randomly so that a representive example s taken.
          • the validlicy and reproducabiltyof the resuts increase as the results from more quadrats are produced.
          • used for slow moving aniimals. e.g. slugs and snails.
    • physical factors
      • tempreture
      • amount of light
      • avalibilty of water
      • avaiblitly of nutrients
      • availability of oxygen and carbon dioxide.
      • predators
    • e.g. daisy plants need more light from the sun in order to make food and complete photodsynthisis. this means that they will be found in light not shady places
      • light ENERGY
    • E.G. grass is found in sunlight of a filed rather than in semi shaded area or woodland. this is because grass needs a lot of light energy to photosynthisise.
    • ecosystems
      • environment- all the conditions that surround a living organism.
      • habitata- the pace in which an organism lives.
      • population- all the members of a single species that live in a habitat.
      • communtity- all the poupulations of differnt organisms that live together in a habitat.
      • ecosystem- acommuntiy and the habitat in whcih it live sin.


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