Describe how the use of insecticides, herbicides, chemical fertilisers and selective breeding each contribute to increasing crop yield in modern farming.

Cambridge International IGCSE Biology (0610) — 20.1 Food supply · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Insecticides kill insects that damage or consume crops, reducing crop losses
Herbicides kill weeds, reducing competition with crops for nutrients, water or light
Chemical fertilisers increase the amount of nutrients/mineral salts in the soil, so plants grow larger and produce more fruit
Selective breeding involves choosing and breeding organisms with desirable characteristics (e.g. high yield) so that offspring also have high yield

Examiner tips

  • Use the exact phrases from the mark scheme
  • Show each method separately
  • Keep sentences short and factual
  • Avoid extra explanation

Common mistakes

  • Mixing up insecticides with herbicides
  • Failing to mention the effect of fertilisers on plant size
  • Not specifying that selective breeding aims at high yield

Mark scheme (4 marks)

  1. Insecticides kill insects that damage or consume crops, reducing crop losses
  2. Herbicides kill weeds, reducing competition with crops for nutrients, water or light
  3. Chemical fertilisers increase the amount of nutrients / mineral salts in the soil, so plants grow larger and produce more fruit
  4. Selective breeding involves choosing and breeding organisms with desirable characteristics (e.g. high yield) so that offspring also have high yield

Key terms in this question

insecticides · herbicides · chemical fertilisers · selective breeding · yield

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