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Learn0610Papers 1, 3 · CoreHuman influences on ecosystemsFood production
Human influences on ecosystems · Subtopic 1 of 2

Food Production

Greenhouses and polythene tunnels raise crop yields by controlling limiting factors: higher temperature, extra CO₂ (from paraffin heaters) and artificial light. Fertilisers supply nitrate, phosphate and potassium. Pesticides kill pests but can harm other species and accumulate in food chains; biological control uses a natural predator instead. Fish farming keeps fish in controlled conditions with fed diets and disease control. Monocultures and intensive livestock increase output but reduce biodiversity and can spread disease and pollution.

Cambridge 5090 Paper 1Cambridge 5090 Paper 2Cambridge 0610 Papers 2, 4Cambridge 0610 Papers 1, 3Edexcel 4BI1 Paper 1BEdexcel 4BI1 Paper 2B≈ 35 minRevision 1 · updated 2026-10-30
Section 1 of 14

Learning objectives

  • Explain how greenhouses increase yields.
  • Describe the use of fertilisers and pest control.
  • Describe fish farming and intensive farming, and their problems.
Pause and think

Tomatoes grown in greenhouses can be harvested in winter in northern Europe. How is that possible?

Section 2 of 14

Core idea

Start hereFeeding eight billion

World food production has kept pace with population growth through machines, fertilisers, pesticides and selective breeding, but each brings costs.

The big idea

Controlling limiting factors, adding nutrients and managing pests increases yields. Intensive methods raise output but can harm biodiversity and the environment.

1. Greenhouses

Worked exampleWinter lettuces

A grower wants lettuces in December.

Goal
Suggest three changes.
Strategy
Remove limiting factors.
  1. heating\text{heating}
    Raises temperature towards the optimum.
  2. artificial lighting\text{artificial lighting}
    Longer and brighter days.
  3. extra CO2\text{extra CO}_2
    Often limiting in a closed greenhouse.
AnswerHeat, light and CO₂ enrichment.
✓ CheckOnly worthwhile if the extra yield covers the costs ✓.

2. Pest control

Chemical vs biological control

Trade-offs either way.

Key takeawayIntensive farming Monocultures and intensive livestock are efficient, but reduce biodiversity, spread disease, and rely on antibiotics and pesticides.
Pause and think

Why do fish farms need to control disease carefully?

Summary

  • Greenhouses remove limiting factors.
  • Fertilisers and pest control.
  • Intensive farming has costs.
Key words
Monoculture
Growing one crop over a large area.
Biological control
Using a natural enemy to control a pest.
Yield
Amount of crop produced per area.
HistoryThe Green Revolution. From the 1960s, Norman Borlaug's high-yield wheat varieties, with fertilisers and irrigation, helped India and Pakistan double wheat production, preventing famine for millions.
Fun factBumblebee workers. Commercial greenhouses buy boxes of bumblebees to pollinate tomatoes; their buzzing shakes pollen loose.
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