3.7.4 - Populations in Ecosystems

Question 1

community

Answer 1

all the populations of different species living and interacting in a particular place at the same time (populations of different species form a community)

Question 2

Describe and explain how succession
occurs.

Answer 2

• (colonisation by) pioneer species
• pioneers/species/organisms change the
  environment/habitat/conditions/factors
• environment becomes less hostile/more suitable for other/new species/less suitable for previous species
• change/increase in diversity/biodiversity
• climax community

Question 3

mark-release-recapture method

Answer 3

• capture/collect/sample, mark and release
• leave time for individuals to disperse before second sampling/collection
• population size = (number in first sample × number in second sample) / number of marked individuals recaptured

Question 4

sampling quadrat

Answer 4

• method of randomly determining position (of quadrats) e.g. random number generator
• large number/sample of quadrats
• divide total percentage by number of
  quadrats/samples/readings