Describe the importance of biodiversity and explain how human activities can reduce it.

Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 2.5 Biodiversity · Describe / Explain · 5 marks · View as Markdown

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

Tropical rainforests contain millions of species of organisms. In recent decades, large areas of rainforest have been cleared to make way for agriculture and urban development.

Model answer (5 marks)

Biodiversity is the variety of species in an area or on Earth.

High biodiversity is important because it gives ecosystem stability and resilience – if one species declines the ecosystem can still function.

It also provides resources for humans, such as medicines, food and raw materials.

Human activities reduce biodiversity. Deforestation and land conversion for agriculture remove habitats, so fewer species can survive. Pollution, over‑hunting, over‑fishing and the introduction of invasive species also lower species numbers.

Examiner tips

Use the exact terms ‘biodiversity’, ‘ecosystem stability’, ‘resilience’, ‘medicine, food, raw materials’.
Show the cause–effect link: human activity → habitat loss or species decline → reduced biodiversity.
Keep the answer concise – 5 marks, so one sentence per point.
Use the word ‘reduces’ or ‘lowers’ to describe the impact of human actions.

Common mistakes

Using vague words like ‘variety’ without saying ‘biodiversity’.
Failing to mention the specific benefits (medicine, food, raw materials).
Omitting the link between habitat loss and species decline.

Mark scheme (5 marks)

Biodiversity refers to the variety of different species found in an area / on Earth
High biodiversity is important for ecosystem stability / resilience, so that if one species declines the ecosystem can continue to function
High biodiversity provides resources for medicine / food / raw materials that benefit humans
Deforestation / clearing land for agriculture removes habitats, reducing the number of species that can live there
Other human activities such as pollution, over-hunting / over-fishing, or introduction of invasive species also reduce biodiversity by decreasing species numbers

Key terms in this question

biodiversity