# Explain how negative feedback mechanisms contribute to the stability of populations within an ecosystem.

> IB DP Biology Standard Level (2023 syllabus) — D4.2 Stability and change · Explain · 4 marks

> Many ecosystems maintain relatively stable population sizes over time despite fluctuations in environmental conditions. This stability arises from regulatory mechanisms that respond to changes in population density.

## Mark scheme (4 marks)

1. Negative feedback occurs when a deviation from a set point (or equilibrium) triggers a response that reverses / opposes that deviation.
2. As population size increases, limiting factors such as food availability, predation, or disease intensify, increasing mortality / reducing reproductive rate.
3. As population size decreases below equilibrium, limiting factors relax, allowing birth rate to exceed death rate and population numbers to recover.
4. These opposing responses maintain the population near a dynamic equilibrium (carrying capacity / K), contributing to ecosystem stability.

## Key terms

- [negative feedback](https://www.gradenine.co.uk/glossary/negative-feedback)

## Related

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-negative-feedback-mechanisms-contribute-0e483974) · Published by Druglandscape Ltd.