CCEA A Level Biology
CCEA A Level Biology 2.4 Human Impact on Biodiversity Exam Questions
Free CCEA A Level Biology revision for 2.4 Human Impact on Biodiversity: what you need to know, common mistakes and exam-style questions with answers. Covers agriculture and biodiversity, monoculture, hedgerows, biological control, waterway pollution, eutrophication, BOD, conservation designations in Northern Ireland and climate change.
Practise 2.4 Human Impact on Biodiversity with past papers
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About CCEA A Level Biology 2.4 Human Impact on Biodiversity
Section 2.4 of Unit AS 2 looks at how human activity reduces biodiversity and what can be done about it, with a strong Northern Ireland focus. You need the effects of intensive agriculture such as monoculture and hedgerow removal, and alternatives like crop rotation, field margins and integrated pest management. Waterway pollution from slurry and silage effluent (organic) and fertiliser run-off (eutrophication) is assessed through biological oxygen demand and effects on flora and fauna. CCEA also names conservation measures: ASSIs, Special Areas of Conservation, Biodiversity Action Plans and agri-environment schemes. Finally, you need the effects of climate change on species ranges and extinctions. Essay questions on this section are common.
What you need to know
- Agriculture Monoculture and hedgerow removal reduce habitat and species diversity. Polyculture, crop rotation, hedgerow conservation and predator strips at field margins help maintain biodiversity.
- Pest control Pesticides can kill non-target species and bioaccumulate. Integrated pest management combines biological control with limited, targeted chemical use.
- Organic pollution Slurry and silage effluent add organic matter; bacteria decompose it, using oxygen and raising the biological oxygen demand (BOD). Fish and invertebrates that need high oxygen die.
- Eutrophication Fertiliser run-off adds nitrate and phosphate, causing algal blooms. Light is blocked, plants die, decomposers increase and oxygen falls.
- Conservation in Northern Ireland Areas of Special Scientific Interest, Special Areas of Conservation, Biodiversity Action Plans, agri-environment schemes and Northern Ireland priority habitats and species lists protect biodiversity.
- Climate change Global warming causes local extinctions and shifts in species ranges, which alter the biodiversity of species and ecosystems.
Common mistakes in 2.4 Human Impact on Biodiversity
- Saying algae use up the oxygen in eutrophication. The main oxygen demand comes from aerobic bacteria decomposing dead algae and plants.
- Confusing BOD with oxygen concentration. A high BOD means a lot of organic material and microbial activity, so dissolved oxygen will be low.
- Saying biological control eliminates the pest. It reduces the pest population to a level that is not economically damaging.
- Giving vague answers such as farming is bad for wildlife. Name the specific practice and the mechanism of biodiversity loss.
- Treating global warming only as rising temperature. Link it to range shifts, local extinctions and changes in community composition.
Try three 2.4 Human Impact on Biodiversity exam-style questions
1. Explain how fertiliser run-off can lead to the death of fish in a lake. (5 marks)
Show the mark scheme answer
Nitrate and phosphate enter water; rapid algal growth or algal bloom; blocks light so submerged plants die; algae and plants die and are decomposed by aerobic bacteria; bacteria use up oxygen (high BOD); fish die from lack of oxygen.
2. Give two ways farmers can increase biodiversity on farmland. (2 marks)
Show the mark scheme answer
Conserve or replant hedgerows; leave field margins or predator strips; crop rotation or polyculture; integrated pest management (any two).
3. Suggest why climate change may lead to local extinction of a species. (2 marks)
Show the mark scheme answer
Conditions move outside the species' tolerance range; species cannot migrate quickly enough or has nowhere suitable to move to.
2.4 Human Impact on Biodiversity FAQs
What does CCEA A Level Biology 2.4 Human Impact on Biodiversity cover?
It covers agriculture, pest control, organic and inorganic water pollution, BOD, conservation measures in Northern Ireland and climate change.
Which unit is 2.4 Human Impact on Biodiversity examined in?
It is examined in Unit AS 2: Organisms and Biodiversity, a 1 hour 30 minute written paper of structured questions and an essay.
Which conservation measures should I name?
Areas of Special Scientific Interest, Special Areas of Conservation, Biodiversity Action Plans and agri-environment schemes, plus Northern Ireland priority habitat and species lists.
