AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to explain how a change in an abiotic factor would…
Full specification wording
Abiotic factors: Students should be able to explain how a change in an abiotic factor would affect a given community given appropriate data or context.
A community is all the populations of different species living together in a habitat.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 3
Study notes
From the checked teaching notes for this specification point.
The idea
A community is all the populations of different species living together in a habitat. Abiotic factors are the non-living conditions of that habitat, such as light intensity, temperature, moisture, soil pH and mineral content, wind, carbon dioxide for plants and oxygen for aquatic animals. To explain an effect, identify the factor that has changed, state the direction of change, then trace the consequence through the organisms. For example, if light intensity falling in a wood reduces photosynthesis in ground plants, their growth slows, so herbivores have less food and their numbers may fall, which can also reduce predator numbers. Always link the changed factor to a named process such as photosynthesis, enzyme activity, transpiration or gas exchange, then to survival, reproduction and population size.
What earns the marks
- Identifies the specific abiotic factor that has changed and states whether it has increased or decreased.
- Links the changed factor to a named biological process, such as photosynthesis, enzyme activity, transpiration or gas exchange.
- Explains the consequence for survival or reproduction of organisms in the community.
- Traces the effect through more than one trophic level or species where the data or context allows.
- Uses the data or context provided, quoting values or trends, rather than giving a generic answer.
- Uses correct ecological terminology, including community, population, habitat and abiotic.
Common mistakes and how to put them right
Describing the factor without explaining a consequence.
Put it right: State the effect on a named process and then on the organism.
Treating a biotic factor, such as predation, as abiotic.
Put it right: Check whether the factor is living or non-living before answering.
Giving a one-step answer that stops at the plant.
Put it right: Continue the chain to consumers and, where relevant, decomposers.
Exam tips
- Underline the factor and the direction of change in the question before you start writing.
- Use the connectives because, so and therefore to build a logical chain from factor to population.
- If data are given, quote at least one value or trend and explain what it shows about the community.
Try the lesson
The start of the Abiotic factors: Students should be able to explain how a change in an abiotic factor would affect a given community given appropriate data or context. lesson, made from checked teaching notes for this specification point.
Have a go first
A woodland community contains oak trees, caterpillars that eat oak leaves and blue tits that eat caterpillars. A survey shows that light intensity reaching the oak leaves has decreased because taller trees now shade them. What is the most likely effect on this community?
Listen
A community is all the populations of different species living together in a habitat. Abiotic factors are the non-living conditions of that habitat, such as light intensity, temperature, moisture, soil pH and mineral content, wind, carbon dioxide for plants and oxygen for aquatic animals. To explain an effect, identify the factor that has changed, state the direction of change, then trace the consequence through the organisms. For example, if light intensity falling in a wood reduces photosynthesis in ground plants, their growth slows, so herbivores have less food and their numbers may fall, which can also reduce predator numbers. Always link the changed factor to a named process such as photosynthesis, enzyme activity, transpiration or gas exchange, then to survival, reproduction and population size. A strong answer earns marks for these points. Identifies the specific abiotic factor that has changed and states whether it has increased or decreased. Links the changed factor to a named biological process, such as photosynthesis, enzyme activity, transpiration or gas exchange. Explains the consequence for survival or reproduction of organisms in the community. Traces the effect through more than one trophic level or species where the data or context allows. A common slip: Describing the factor without explaining a consequence. Instead, state the effect on a named process and then on the organism. Exam tip: Underline the factor and the direction of change in the question before you start writing.
See it
Put it in order
Put these steps in the order they happen.
- 1. Link to named process: photosynthesis, enzyme activity, transpiration or gas exchange
- 2. State direction of change
- 3. Abiotic factor changes
- 4. Effect traced to another species or trophic level
- 5. Effect on population size
- 6. Effect on survival or reproduction
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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