LEARNING OBJECTIVES
By the end of this chapter, you should be able to:
- evaluate food production
- explain habitat destruction
- describe pollution and eutrophication
- explain sustainable conservation
THE BIG IDEA
How food production, habitat change, pollution and conservation alter biodiversity.
This chapter builds each process from its structures, inputs and outputs. Follow the connections rather than memorising isolated facts, then use precise biological terms when explaining cause and effect.
SECTION 01
Food supply
Machinery, fertilisers, insecticides, herbicides and selective breeding increase yield or efficiency but may create environmental and welfare costs.
DETAILED EXPLANATION
- Monocultures simplify harvesting and give uniform products, but reduce diversity and increase pest vulnerability.
- Intensive livestock increases output in limited space, but raises disease, waste and welfare concerns.
SECTION 02
Habitat destruction
Biodiversity is the number of species in an area. Housing, farming, extraction and pollution destroy habitats and alter food webs.
DETAILED EXPLANATION
- Deforestation reduces biodiversity and may cause extinction.
- Less root binding and interception increase erosion and flooding.
- Less photosynthesis and burning raise carbon dioxide.
- Introduced species may outcompete or prey on native species.
SECTION 03
Pollution and eutrophication
Sewage and fertiliser add mineral ions. Persistent plastics entangle or are eaten by animals. Carbon dioxide and methane enhance greenhouse warming and climate change.
DETAILED EXPLANATION
- Eutrophication: nutrients rise → producers bloom → die → decomposers respire → dissolved oxygen falls → oxygen-dependent organisms die.
SECTION 04
Conservation
A sustainable resource is replaced as rapidly as removed. Conservation maintains biodiversity, ecosystem functions and resources.
DETAILED EXPLANATION
- Forests: protected areas, quotas, replanting, monitoring and education.
- Fish: closed seasons, reserves, quotas, mesh controls and monitoring.
- Species: habitat protection, captive breeding, artificial insemination, IVF and seed banks.
- Small populations lose genetic variation and become more vulnerable.
QUICK CHAPTER SUMMARY
The ideas to carry forward
- Food methods have trade-offs.
- Habitat loss reduces biodiversity.
- Eutrophication removes dissolved oxygen.
- Greenhouse gases alter climate.
- Sustainable management balances removal and replacement.