Communities — AQA GCSE Biology
Test yourself on Communities with AQA GCSE practice questions.
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Communities explained
A stable community has all species and environmental factors in balance, so population sizes stay fairly constant over time.
Read the full explanation
Stability does not mean nothing changes; it means changes are small or self-correcting. For example, if a predator's population rises, prey numbers may fall, which reduces food for the predator and its numbers fall again. Environmental factors such as temperature, water and light also remain suitable. A stable community therefore resists small disturbances and maintains biodiversity. If a major factor changes, such as a new predator or a drought, the balance can be lost and populations may change significantly.
Your focus
- Describe the features of a stable community.
- Explain how balance between species and environmental factors keeps population sizes fairly constant.
- Evaluate whether data from a community shows stability or change.
Communities exam tips
Marking Points
- States that a stable community has species and environmental factors in balance.
- Explains that population sizes remain fairly constant rather than changing dramatically.
- Recognises that stability involves small fluctuations that are corrected by negative feedback.
- Gives an example of a factor, such as food supply or predation, that helps maintain balance.
- Explains that a major environmental change can destabilise a community and alter population sizes.
Examiner Tips
- 💡Use the phrase fairly constant when describing population sizes in a stable community.
- 💡Refer to both species and environmental factors to cover all parts of the definition.
- 💡When interpreting data, look for small fluctuations around a mean rather than a perfectly flat line.
Common Mistakes
- Thinking stable means no change at all; correct by explaining that populations fluctuate slightly but remain fairly constant.
- Assuming only living factors matter; correct by including environmental factors such as temperature, light and water.
- Believing a stable community cannot be affected by change; correct by stating that large disturbances can upset the balance.