• problems with investigating where organisms live occur because there are loads of different organisms and they live all over the place, to overcome biologists record their distribution and the population in that area
  • different populations live in a community and biologists look for relationships between the organisms through the way their distributions overlap
  • biologists use sampling which maeans counting a small number of the whole population and working out a total
  • quadrats can be used for plants, transect lines are used to count the number of organisms that touch it or can be combined with quadrats, nets can catch animals like butterflies or fish, pooters can **** in small animals and pitfall traps collect small animals
  • capture recapture is when you count, mark and release a first sample, recapture a second sample and count the number of previously marked organisms in the second sample
  • apparature should be big enough and the experiment should be reliable and fair (same equipment, placed fairly. randomly)
  • biologists assume no death, immagration or emmigration occured, also they make sure the marking does not affect their survival
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  • keys can be spider keys or numbered keys
  • ecosystems include all the living things in the area and how they interact with eachother and the physical conditions around them - ecosystems are also self sufficient so nothing is supplied but the sun's energy - natural ecosystems are woodlands, lakes, seashore and often contain loads of organisms so have a large biodiversity
  • oganisms on a beach are not randomly placed because of the effect of physical factors and the effect of other organisms - two species in the same ecosystem living in different parts is called zonation which is due to physical factors and competition between the two speciers
  • artificial ecosystems are made by humans such as fish farms and gardens - they have a low biodiversity as humans often control what organisms live in that artifical ecosystem and remove unwanted species
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