Explain how interdependence between organisms in a community means that a change in one population can affect many other populations.

AQA GCSE Biology (8461) — 4.7.2 Organisation of an ecosystem · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

In a meadow ecosystem, a disease kills most of the rabbit population. Rabbits eat grass and are eaten by foxes.

Model answer (4 marks)

Organisms in a community depend on each other for resources such as food, shelter and pollination. A fall in rabbit numbers means less food is available for foxes, so the fox population decreases. With fewer rabbits eating grass, the grass (producer) population increases. This shows that a change to one population disrupts the whole community and affects multiple trophic levels.

Examiner tips

  • Use the word "interdependence" to link the points
  • Show the chain of effects: rabbit → fox → grass
  • Mention trophic levels explicitly
  • Keep each point short and to the point

Common mistakes

  • Mixing up cause and effect (e.g. saying foxes eat grass)
  • Omitting the effect on the producer population
  • Using vague terms like "more food" without specifying which species

Mark scheme (4 marks)

  1. Organisms in a community depend on each other for resources such as food / shelter / pollination
  2. A fall in rabbit numbers means less food is available for foxes, so the fox population decreases
  3. With fewer rabbits eating grass, the grass / producer population increases
  4. This shows that a change to one population disrupts the whole community / affects multiple trophic levels

Key terms in this question

interdependence · community · population

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