How do humans damage ecosystems, and how can we protect biodiversity?
The effect of human activities on the environment, including pollution, eutrophication, global warming and deforestation, the meaning and importance of biodiversity, and methods of conservation.
A focused answer to the WJEC GCSE Biology section 1.6 topic on human impact, covering pollution and eutrophication, global warming and deforestation, the meaning and importance of biodiversity, the causes of its loss, and methods of conservation and sustainable use of resources.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
WJEC wants you to describe how human activities damage the environment (pollution, eutrophication, global warming, deforestation), explain what biodiversity is and why it matters, and describe methods of conservation.
Pollution
The growing human population uses more resources and produces more waste, causing pollution of the air, water and land.
- Air pollution: burning fossil fuels releases sulfur dioxide (which causes acid rain), carbon monoxide and particulates, as well as carbon dioxide (which contributes to global warming).
- Water pollution: sewage, fertilisers and industrial waste washed into rivers and lakes harm the organisms living there.
- Land pollution: litter, pesticides and other chemicals damage habitats and can build up in food chains.
Eutrophication
Eutrophication is the damage caused when too many nutrients (from fertilisers or sewage) enter a body of water. The sequence is:
- Extra nitrates and phosphates enter the water.
- Algae and water plants grow rapidly, forming an algal bloom on the surface.
- The bloom blocks light from reaching the plants below.
- Those plants cannot photosynthesise, so they die.
- Decomposers break down the dead material, respiring and using up the oxygen in the water.
- With little oxygen left, fish and other animals cannot respire and die.
Global warming and deforestation
Burning fossil fuels releases extra carbon dioxide, a greenhouse gas. Greenhouse gases trap heat in the atmosphere (the greenhouse effect), and the extra carbon dioxide enhances this, causing global warming. Possible consequences include rising sea levels, changing climates and the loss of habitats.
Deforestation (cutting down forests) makes this worse in two ways: it removes trees that would have absorbed carbon dioxide by photosynthesis, and burning the wood releases more carbon dioxide. Deforestation also destroys habitats, reducing biodiversity, and can cause soil erosion.
Biodiversity and conservation
Biodiversity is reduced by pollution, habitat destruction, overfishing, hunting and climate change. It can be protected by conservation, which includes:
- protecting habitats by creating nature reserves and national parks,
- running captive breeding programmes for endangered species,
- storing seeds in seed banks,
- replanting forests (reforestation),
- legal protection of endangered species.
Humans also need to use resources sustainably, meaning meeting today's needs without using up resources or damaging the environment so much that future generations suffer.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style6 marksDescribe how fertiliser running off farmland into a river can lead to the death of fish. Use the term eutrophication.Show worked answer →
A 6-mark extended question on eutrophication. Mark it for a clear, ordered sequence.
Fertiliser running into the river adds extra nitrates and phosphates to the water. This causes algae and water plants to grow rapidly, forming an algal bloom on the surface. The bloom blocks light from reaching the plants below, so they cannot photosynthesise and they die. Decomposers (bacteria) break down the dead plants and algae, and as they do so they respire and use up the oxygen dissolved in the water. With little oxygen left, the fish and other animals cannot respire, so they die.
A top answer gives the full sequence in order: nutrients, algal bloom, light blocked, plants die, decomposers respire and use up oxygen, animals die. Reward the precise link that the decomposers use up the oxygen. Missing the oxygen step is the most common reason to lose marks.
WJEC style4 marksExplain what is meant by biodiversity and give two ways it can be conserved.Show worked answer →
A 4-mark question.
Biodiversity is the variety of different species (and the variety within them) in an ecosystem or on Earth. A high biodiversity makes an ecosystem more stable and provides resources for humans.
Two ways to conserve it: protect habitats by creating nature reserves or national parks; run captive breeding programmes for endangered species; use seed banks to store plant seeds; or replant forests (reforestation).
Markers reward: a correct definition of biodiversity, plus two valid conservation methods. Just naming "looking after animals" without a specific method does not gain the marks.
Related dot points
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A focused answer to the WJEC GCSE Biology section 1.6 topic on feeding relationships, covering food chains and food webs, pyramids of number and biomass, the transfer of energy along a food chain, why energy is lost at each trophic level, and the implications for food production.
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A focused answer to the WJEC GCSE Biology section 1.6 topic on nutrient cycles, covering the carbon cycle and the roles of photosynthesis, respiration, combustion and decomposition, the nitrogen cycle and its bacteria, the role of decomposers, and the conditions that affect the rate of decay.
- Photosynthesis as the process that makes glucose using light energy, its word and symbol equations, the limiting factors of light, carbon dioxide and temperature, and the required practicals.
A focused answer to the WJEC GCSE Biology section 1.5 topic on photosynthesis, covering photosynthesis as the process that uses light energy to make glucose, its word and symbol equations, the limiting factors of light intensity, carbon dioxide and temperature, and the required practicals on starch production and rate.
- Transpiration as the loss of water vapour from a plant, the transpiration stream, the factors that affect the rate of transpiration, and the role of stomata and guard cells.
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Sources & how we know this
- WJEC GCSE Biology specification (from 2016) — WJEC (2016)