How do human activities damage ecosystems, and how can we conserve them sustainably?
Human impact on the environment: the effects of deforestation, agriculture and pollution; eutrophication; the loss of biodiversity; climate change; and conservation and sustainability.
A focused answer to the Eduqas Component 1 statement on human impact. Covers deforestation and agriculture, eutrophication, the loss of biodiversity, climate change from greenhouse gases, and conservation and sustainability strategies.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
Eduqas wants you to explain the effects of deforestation, agriculture and pollution, explain eutrophication, explain the loss of biodiversity and climate change, and describe conservation and sustainability. This topic closes Component 1 by applying ecology to human activity.
Deforestation, agriculture and pollution
Deforestation removes habitats (reducing biodiversity), reduces a major carbon sink (so more carbon dioxide stays in the air), and can cause soil erosion. Intensive agriculture replaces diverse natural communities with monocultures, removes hedgerows (habitats and corridors), and uses fertilisers and pesticides that can leach into water or kill non-target species. Pollution (from sewage, fertilisers, plastics and chemicals) damages organisms directly or indirectly.
Eutrophication
Loss of biodiversity and climate change
Habitat destruction, overexploitation, pollution and introduced species all reduce biodiversity, lowering an ecosystem's resilience and the gene pool available for future use (in medicine and agriculture). Climate change is driven by the enhanced greenhouse effect: greenhouse gases such as carbon dioxide and methane absorb and re-emit long-wave (infrared) radiation, trapping heat so the mean global temperature rises. Consequences include melting ice and rising sea levels, shifts in species ranges and migration timing, more extreme weather and coral bleaching.
Conservation and sustainability
Strategies include protected areas (reserves and national parks), sustainable harvesting (fishing quotas, selective logging with replanting), captive breeding and reintroduction, seed banks, and reducing emissions. Many decisions involve balancing economic needs against conservation, which Eduqas may ask you to evaluate.
Examples in context
Example 1. Fishing quotas. Limiting the catch and net mesh size lets fish breed before being caught, keeping the population above the level needed to recover, a real sustainability measure that Eduqas may ask you to justify.
Example 2. Reforestation as a carbon sink. Planting trees removes carbon dioxide by photosynthesis and stores it in biomass, partially offsetting emissions while restoring habitat, linking the carbon cycle to conservation.
Try this
Q1. State what is meant by eutrophication. [1 mark]
- Cue. The enrichment of water with mineral nutrients (such as nitrate or phosphate).
Q2. Explain why dissolved oxygen falls in a eutrophic lake. [3 marks]
- Cue. Nutrients cause an algal bloom that blocks light; plants die; decomposers feed on the dead material and respire aerobically, using up the dissolved oxygen.
Q3. Explain how carbon dioxide contributes to global warming. [2 marks]
- Cue. It is a greenhouse gas that absorbs and re-emits long-wave (infrared) radiation, trapping heat in the atmosphere and raising the mean global temperature.
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20196 marksExplain how the leaching of nitrate fertiliser into a river can lead to the death of fish, using the term eutrophication in your answer.Show worked answer →
Nitrate fertiliser leaches into the river and increases the concentration of nitrate (a mineral nutrient) in the water; this is eutrophication.
The extra nitrate causes rapid growth of algae at the surface (an algal bloom), which blocks light from reaching plants below.
The submerged plants cannot photosynthesise and die, and the algae also die as nutrients run out.
Saprobiotic (decomposer) bacteria feed on the dead plants and algae and multiply; their aerobic respiration uses up the dissolved oxygen in the water.
With little dissolved oxygen, fish and other aerobic organisms cannot respire enough and die.
Markers reward enrichment with nitrate, an algal bloom blocking light, plants dying, decomposers respiring and using oxygen, and fish dying from lack of oxygen.
Eduqas 20214 marksExplain how the increase in atmospheric carbon dioxide concentration contributes to global warming, and give two consequences for ecosystems.Show worked answer →
Carbon dioxide is a greenhouse gas: it absorbs and re-emits long-wave (infrared) radiation from the Earth, trapping heat in the atmosphere, so the mean global temperature rises (the enhanced greenhouse effect).
Two consequences (any two): the melting of ice and rising sea levels flooding coastal habitats; shifts in species distribution or migration timing; more extreme weather; coral bleaching; or changes to the ranges of pests and diseases.
Markers reward carbon dioxide absorbing and re-emitting long-wave radiation to trap heat, and two valid consequences for ecosystems.
Related dot points
- Population size and ecosystems: factors limiting population size; sampling techniques; succession; the flow of energy through trophic levels; and the carbon and nitrogen cycles.
A focused answer to the Eduqas Component 1 statement on populations and ecosystems. Covers density-dependent and independent factors, sampling with quadrats and transects, succession, energy flow through trophic levels, and the carbon and nitrogen cycles.
- Microbiology: the culturing of microorganisms; aseptic technique; the bacterial growth curve; methods of measuring population growth; and the action of antibiotics.
A focused answer to the Eduqas Component 1 statement on microbiology. Covers culturing microorganisms on agar, aseptic technique, the bacterial growth curve and its phases, methods of counting populations, and how antibiotics act.
- Classification and biodiversity: the three domains and the taxonomic hierarchy; phylogeny; the species concept; measuring biodiversity using the index of diversity; and genetic diversity.
A focused answer to the Eduqas Component 2 statement on classification and biodiversity. Covers the three domains and taxonomic hierarchy, phylogeny, the species concept, the index of diversity calculation, and genetic diversity.
- Photosynthesis: chloroplast structure; the light-dependent stage (photolysis of water, photophosphorylation and the reduction of NADP); the light-independent stage (the Calvin cycle); and the effect of limiting factors.
A focused answer to the Eduqas Component 1 statement on photosynthesis. Covers chloroplast structure, the light-dependent stage (photolysis, photophosphorylation and reduced NADP), the light-independent stage (the Calvin cycle with RuBP, GP and TP), and limiting factors.
- Respiration: glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation; the role of NAD and FAD; anaerobic respiration; and respiratory substrates.
A focused answer to the Eduqas Component 1 statement on respiration. Covers glycolysis, the link reaction, the Krebs cycle, oxidative phosphorylation and chemiosmosis, the role of NAD and FAD, anaerobic respiration, and respiratory substrates.
Sources & how we know this
- Eduqas A Level Biology Specification (A400) — Eduqas (2015)