Explain why using pesticides to increase crop yields can cause problems for ecosystems.

Eduqas GCSE Biology — 6.4 Biological challenges of increasing food yields · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Pesticides kill non‑target organisms such as bees and other pollinators, reducing pollination and biodiversity.
Pesticides can bioaccumulate and biomagnify, so top predators in the food chain become highly toxic.
Loss of prey or plant species limits food for other organisms, disrupting food webs.
Pests develop resistance, requiring higher doses or new chemicals, which further harms the environment.

Examiner tips

  • Use the word ‘kill’ or ‘destroy’ for non‑target species, mention pollinators. Mention bioaccumulation/biomagnification explicitly. Show the link between loss of species and food‑web disruption. Explain resistance as a cause for increased chemical use.

Common mistakes

  • Not naming pollinators or other non‑target species. Confusing bioaccumulation with biomagnification. Forgetting to link species loss to food‑web disruption. Ignoring the resistance issue or stating it as a benefit.

Mark scheme (4 marks)

  1. Pesticides can kill organisms other than the target pest (non-target species / beneficial insects such as bees / pollinators)
  2. Pesticides can accumulate / build up in food chains (bioaccumulation / biomagnification), reaching toxic concentrations in top predators
  3. Reduction in prey / plant species can reduce food availability for other organisms, disrupting food webs
  4. Pests can develop resistance to pesticides over time, meaning higher doses or new pesticides are needed, causing further environmental damage

Key terms in this question

pesticides

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