How do humans affect the environment, and how can we reduce the damage?
The causes and effects of pollution including water and air pollution, the use of indicator species to monitor pollution, the consequences of habitat destruction and deforestation, and conservation measures to protect biodiversity.
A focused CCEA GCSE Biology answer on human impact, covering the causes and effects of water and air pollution, indicator species, habitat destruction and deforestation, and conservation measures to protect biodiversity.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
CCEA wants you to describe the causes and effects of water and air pollution, explain how indicator species monitor pollution, describe the consequences of habitat destruction and deforestation, and describe conservation measures.
Water pollution and eutrophication
Sewage and other waste can pollute water in the same way, by adding nutrients and using up oxygen.
Air pollution
Burning fossil fuels releases gases that pollute the air. Sulfur dioxide and nitrogen oxides cause acid rain, which damages trees, lakes and buildings. Carbon dioxide adds to the greenhouse effect and global warming, and carbon monoxide is a poisonous gas.
Indicator species
Habitat destruction and conservation
Deforestation and other habitat destruction reduce biodiversity by removing the places organisms live, and deforestation also reduces photosynthesis and increases carbon dioxide. Conservation measures protect biodiversity: creating protected areas and nature reserves, replanting trees, controlling pollution, and protecting endangered species.
Examples in context
Example 1. Lichens and clean air. Lichens are sensitive to sulfur dioxide, so they only grow well where the air is clean. Surveying which lichens grow on trees and walls in different parts of a city shows where the air is most polluted, often near busy roads. This use of an indicator species needs no expensive equipment and gives a long-term picture, which is why it is a classic CCEA monitoring example.
Example 2. Why deforestation is a double problem. Cutting down a forest destroys the habitat of many species, reducing biodiversity, and it removes trees that were absorbing carbon dioxide in photosynthesis. Burning the wood releases yet more carbon dioxide. So deforestation both reduces the removal of carbon dioxide and increases its release, adding to global warming. Linking the loss of habitat to the carbon cycle is the kind of connected reasoning CCEA rewards.
Try this
Q1. What is an indicator species? [1 mark]
- Cue. A species whose presence or absence shows the level of pollution.
Q2. Give one conservation measure that protects biodiversity. [1 mark]
- Cue. Creating protected areas (or replanting trees, or reducing pollution).
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA 20205 marksExplain how fertiliser running off farmland can cause the death of fish in a river (eutrophication).Show worked answer →
Five marks for the ordered chain of eutrophication.
Fertiliser (containing nitrates) runs off the land into the river, adding extra nutrients to the water.
The extra nutrients cause algae and water plants to grow rapidly, forming an algal bloom that covers the surface.
The bloom blocks light from reaching the plants below, so they cannot photosynthesise and they die.
Decomposer bacteria break down the dead plants and algae, and the bacteria multiply and respire, using up the dissolved oxygen in the water.
With little oxygen left, the fish and other animals suffocate and die.
Markers reward nutrients in, algal bloom, plants die from lack of light, bacteria use up oxygen, fish die.
CCEA 20193 marksExplain how indicator species can be used to measure water pollution.Show worked answer →
Three marks for the idea of pollution tolerance.
Some species can only survive in clean water (for example mayfly larvae), while others can survive in polluted water (for example bloodworms or rat-tailed maggots).
By recording which species are present in a sample of water, you can judge how polluted the water is.
Clean-water indicator species present means low pollution; only pollution-tolerant species present means high pollution.
Markers reward species with different tolerances, recording which are present, and using this to judge the pollution level.
Related dot points
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Sources & how we know this
- CCEA GCSE Biology specification — CCEA (2017)