A farmer converts a species-rich wildflower meadow into a field of a single crop variety. Explain how this change affects biodiversity and what consequences this could have for the stability of the ecosystem.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Species-rich wildflower meadows can contain over 150 species of flowering plant, along with hundreds of species of insects, birds and small mammals. Modern intensive farming often replaces these meadows with monoculture crops — single-species plantations managed with pesticides and herbicides.
Model answer (5 marks)
Converting the meadow to a monoculture reduces biodiversity – the number of plant, insect, bird and mammal species falls sharply.
The use of pesticides and herbicides kills many non‑crop organisms, further lowering species numbers.
With fewer species the food web becomes simpler and less complex; there are fewer feeding relationships.
If one species is removed or declines, the impact on other species is larger because there are fewer alternative food sources – the ecosystem becomes less stable.
High biodiversity, by contrast, provides many alternative food sources and functional redundancy, so the ecosystem is more stable when species are lost.
The use of pesticides and herbicides kills many non‑crop organisms, further lowering species numbers.
With fewer species the food web becomes simpler and less complex; there are fewer feeding relationships.
If one species is removed or declines, the impact on other species is larger because there are fewer alternative food sources – the ecosystem becomes less stable.
High biodiversity, by contrast, provides many alternative food sources and functional redundancy, so the ecosystem is more stable when species are lost.
Examiner tips
- Mention the loss of species and the use of chemicals; link to food‑web simplification and reduced stability; use terms like ‘biodiversity’, ‘food web’, ‘alternative food sources’, ‘functional redundancy’
- Show causal chain: monoculture → fewer species → simpler food web → less stability
Common mistakes
- Failing to mention pesticides/herbicides; describing only the loss of plant species; not linking reduced biodiversity to ecosystem stability
Mark scheme (5 marks)
- Converting the meadow to a monoculture reduces biodiversity / the number of different species decreases
- Use of pesticides / herbicides kills non-crop species, further reducing biodiversity
- Lower biodiversity means fewer feeding relationships / food web becomes simpler / less complex food web
- If one species is removed / declines, other species are more severely affected / less stable ecosystem
- High biodiversity increases ecosystem stability because organisms can use alternative food sources / species can fill the role of a lost species
Key terms in this question
Related
- All Pearson Edexcel A-Level Biology A (9BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Biodiversity questions
- Biodiversity is important for the stability of ecosystems. Explain why a reducti…
- Describe the importance of biodiversity and explain how human activities can thr…
- A conservation organisation is working to protect a rainforest region that conta…
- A wildlife charity is monitoring two woodland habitats: Habitat A, which has bee…