Explain why maintaining high biodiversity is important for the long-term survival of ecosystems.

WJEC GCSE Biology (Wales) — 2.1.2 Biodiversity · Explain · 4 marks · View as Markdown

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

Scientists have warned that human activities are reducing biodiversity across the planet at an unprecedented rate. Many ecologists argue that losing biodiversity puts entire ecosystems at risk of collapse.

Model answer (4 marks)

A greater variety of species provides more food sources within food webs, so there are more options for predators and prey.
If one species disappears, other species can use alternative food sources, reducing the chance of collapse.
A larger pool of species and genes increases the likelihood that populations can adapt to environmental changes.
Many species supply resources, medicines and materials that humans rely on, so loss of biodiversity threatens human welfare.

Examiner tips

Use the exact phrases from the mark scheme (e.g., "greater variety of species", "alternative food sources", "adapt to environmental changes").
Show the link between biodiversity and ecosystem stability before mentioning human benefits.

Common mistakes

Using vague terms like "many species" without explaining the link to food webs or adaptation.
Failing to mention the human welfare aspect or the role of genes in adaptation.

Mark scheme (4 marks)

A greater variety of species means more food sources are available within food webs
If one species is lost, other species can rely on alternative food sources / the ecosystem is less likely to collapse
A greater variety of species / genes means populations are more likely to be able to adapt to environmental changes
Many species provide resources / medicines / materials that humans depend on, so losing biodiversity threatens human welfare

Key terms in this question

biodiversity · ecosystem