Explain how the use of biological pest control and fertilisers together can reduce the negative impacts on biodiversity whilst still maintaining high crop yields.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A farmer grows wheat on a large area of farmland. Neighbouring fields contain a variety of wild plant and insect species. The farmer wants to increase crop yield without harming the surrounding ecosystem.
Model answer (4 marks)
Fertilisers supply essential nutrients such as N, P and K, stimulating plant growth and increasing yield.
Biological pest control uses natural predators or parasites to keep pest numbers low, avoiding synthetic pesticides.
Because no chemical pesticides are applied, non‑target organisms and beneficial insects survive, so local biodiversity is preserved.
The combined use of fertilisers (high yield) and biological control (low pest damage) lets the farmer maintain productivity while minimising ecological harm.
Biological pest control uses natural predators or parasites to keep pest numbers low, avoiding synthetic pesticides.
Because no chemical pesticides are applied, non‑target organisms and beneficial insects survive, so local biodiversity is preserved.
The combined use of fertilisers (high yield) and biological control (low pest damage) lets the farmer maintain productivity while minimising ecological harm.
Examiner tips
- Use the exact terms ‘fertilisers’ and ‘biological pest control’.
- Show the causal link: fertilisers → yield, biological control → pest reduction, both together → high yield + biodiversity.
- Keep each point short and to the point to hit all four marks.
Common mistakes
- Confusing chemical fertilisers with organic ones; examiners only credit the nutrient‑providing role.
- Mentioning chemical pesticides instead of biological control, which loses the biodiversity point.
- Failing to link the two methods together, giving only two of the four marks.
Mark scheme (4 marks)
- Fertilisers provide essential nutrients to the soil / plants, increasing crop growth / yield
- Biological pest control uses living organisms / natural predators to control pest populations without chemical pesticides
- Avoiding chemical pesticides means non-target species / beneficial insects are not harmed, so biodiversity is maintained
- The combination of both methods means crop yield is high (from fertilisers) AND pest damage is reduced (from biological control), sustaining food production
Key terms in this question
fertiliser · biological pest control · biodiversity · crop yield
Related
- Revision notes: Feeding the human race →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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