A nature reserve contains a large variety of plant species, insect species, and bird species. A nearby field used for growing a single crop contains very few species. Compare the biodiversity of the nature reserve with that of the crop field, and suggest one reason why low biodiversity in an ecosystem could be harmful to that ecosystem.

Eduqas GCSE Biology — 6.3 Biodiversity · Compare · 4 marks · View as Markdown

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

Model answer (4 marks)

The nature reserve has higher biodiversity than the crop field
Because the nature reserve contains a greater variety/number of different species
If one species is lost / a disease or pest wipes out the single crop, there are few or no other species to fulfil that role / the ecosystem could collapse
Because there is less variety of food sources / interdependence between species is reduced, so organisms cannot easily adapt to change

Examiner tips

  • Use the word ‘higher’ to show comparison; mention variety/number of species; give a specific consequence of low biodiversity; link to food web and adaptability

Common mistakes

  • Using ‘more’ instead of ‘higher’ for biodiversity; failing to mention the consequence of a single species loss; not linking low biodiversity to reduced food sources or interdependence

Mark scheme (4 marks)

  1. The nature reserve has higher biodiversity than the crop field
  2. Because the nature reserve contains a greater variety/number of different species
  3. If one species is lost / a disease or pest wipes out the single crop, there are few or no other species to fulfil that role / the ecosystem could collapse
  4. Because there is less variety of food sources / interdependence between species is reduced, so organisms cannot easily adapt to change

Key terms in this question

biodiversity · species · ecosystem

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