What is biodiversity, and how are human activities affecting it?
The meaning of biodiversity, the effects of human population growth and resource use, pollution of land, water and air, the impact of deforestation and global warming, and the methods used to maintain biodiversity.
A focused answer to AQA GCSE Biology 4.7.3, covering biodiversity, the effects of human population growth and pollution, deforestation, global warming, and the methods used to maintain biodiversity.
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What this dot point is asking
AQA wants you to define biodiversity, describe how human population growth and increasing resource use damage ecosystems through pollution, deforestation and global warming, and describe the methods used to maintain biodiversity.
What is biodiversity?
The future of the human species on Earth depends on us maintaining a good level of biodiversity. In a community with high biodiversity, the loss of one species is less likely to cause the whole ecosystem to collapse, because other species can fill similar roles.
The impact of human activity
The human population is growing rapidly and the standard of living is increasing, so more resources are used per person and more waste is produced. This puts ecosystems under pressure in several ways.
Other impacts AQA expects you to describe:
- Deforestation: large-scale clearing of forests for timber, farming and biofuel crops reduces the habitats available, so biodiversity falls, and it reduces the carbon dioxide taken in by photosynthesis while burning trees releases stored carbon.
- Global warming: rising levels of carbon dioxide and methane (greenhouse gases) cause the Earth to warm, changing habitats and climate, melting ice and raising sea levels, which threatens many species that cannot adapt or migrate fast enough.
- Destruction of peat bogs: peat forms over thousands of years as plants do not fully decay in waterlogged ground. Decay or burning of drained peat (often for compost) releases stored carbon dioxide and destroys the bog habitat.
Maintaining biodiversity
Scientists and governments use several methods to protect biodiversity:
- Breeding programmes for endangered species to increase their numbers.
- Protection and regeneration of rare habitats so species keep their food and shelter.
- Reintroduction of field margins and hedgerows on farmland where only one type of crop is grown.
- Reducing deforestation and greenhouse gas emissions by governments.
- Recycling resources rather than dumping waste in landfill.
These often involve a conflict between the needs of people (jobs, food, land) and the protection of the environment, which AQA may ask you to discuss.
Try this
Q1. Define biodiversity. [1 mark]
- Cue. The variety of all the different species of organisms on Earth (or in an ecosystem).
Q2. State two ways biodiversity can be maintained. [2 marks]
- Cue. Any two of: breeding programmes, protecting habitats, reducing deforestation, recycling.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20184 marksExplain how deforestation and the increasing release of carbon dioxide can reduce biodiversity.Show worked answer →
A 4-mark explain question rewards two clear chains of reasoning.
Deforestation destroys habitats, so the species that lived there lose food and shelter and their populations fall or become extinct, reducing biodiversity. It also removes trees that would have photosynthesised, so less carbon dioxide is removed from the air, and burning the trees releases more carbon dioxide.
The extra carbon dioxide (and methane) is a greenhouse gas, so it causes global warming. Warming changes habitats and climates faster than some species can adapt or migrate, so they decline, further reducing biodiversity.
Markers reward habitat loss linked to species decline, and carbon dioxide linked to global warming linked to changing habitats.
AQA 20223 marksDescribe three methods that scientists and governments use to maintain or increase biodiversity, and explain how each one helps.Show worked answer →
A 3-mark question rewards three methods each with a reason.
Breeding programmes for endangered species increase their numbers so the species does not become extinct. Protecting and regenerating rare habitats gives species the food and shelter they need to survive. Reducing deforestation preserves habitats and keeps the trees that take in carbon dioxide. Recycling resources reduces the waste sent to landfill, which reduces land pollution.
Markers reward any three named methods, each correctly linked to how it protects biodiversity.
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Sources & how we know this
- AQA GCSE Biology (8461) specification — AQA (2016)