Explain why it is important to maintain high biodiversity within an ecosystem.

AQA A-Level Biology (7402) — 3.4.7 Investigating Diversity · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Many ecosystems around the world are experiencing a decline in biodiversity due to human activities such as deforestation and intensive farming.

Model answer (5 marks)

Biodiversity is the variety of species in an ecosystem.
1. It allows many species to interact as part of food chains and webs.
2. Species depend on each other for food, shelter and other ecological roles.
3. If one species is lost, other species that rely on it may decline or go extinct.
4. A diverse range of species supplies humans with medicines, food and raw materials.
5. High biodiversity makes ecosystems more stable, resistant to change and less likely to collapse.

Examiner tips

Use the exact wording from the mark scheme, e.g. "food chains or webs" and "resources for humans".
Show the link between species interactions and ecosystem stability.
Remember to mention both ecological and human benefits.

Common mistakes

Confusing biodiversity with ecosystem diversity; they are not the same.
Omitting the human resource aspect or the stability aspect of biodiversity.

Mark scheme (5 marks)

Biodiversity refers to the variety of different species living in an area / on Earth
Many species depend on other species for food / shelter / as part of food chains or webs
Loss of one species can cause other species to decline or become extinct
High biodiversity provides resources for humans, including medicines / food sources / raw materials
A more biodiverse ecosystem is more stable / more resistant to environmental change / less likely to collapse

Key terms in this question

biodiversity · ecosystem