Ecology

• A quadrat is a square frame enclosing a known area e.g 1m^2.
• To compare how common an organism is in two sample areas you:

  1)Place a 1m^2 quadrat on the ground at a random point within the first sample area. e.g divide the area into a grid and use a random number generator to pick coordinates.

  2)Count all the organisms within the quadrat.

  3)Repeat steps 1 and 2 as many times as you can.

  4)Work out the mean number of organisms per quadrat within the first sample area.

  5)Repeat steps 1 to 4 in the second sample area

  6)Finally compare the two means.
• Investigation using transects:

  1)Mark out a line in the area you want to study using a tape measure

  2)Then collect data along the line

  3)You can do this by just counting all the organisms you're interested in that touch the line

  4)Or you can collect the data using quadrats. These can be placed next to each other along the line or at intervals, for example every 2 days.
• Habitat- the place where an organism lives.
• Population- all the organisms of one species living in a habitat
• Community- the populations of different species living in a habitat
• Abiotic factors- non-living factors of the environment
• Biotic factors- living factors of the environment
• Ecosystem- the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
• Interdependence is the interaction between two or more organisms where it is mutually beneficial.
• Sampling is to only count a subset of the organisms in a habitat. This is done because it would be impossible/ very time consuming, to count all the organisms.