AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to explain how a change in a biotic factor might…
Full specification wording
Biotic factors: Students should be able to explain how a change in a biotic factor might affect a given community given appropriate data or context.
Biotic factors are the living influences on a community, including food availability, competition between species, predation and the availability of mates.
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
Biotic factors are the living influences on a community, including food availability, competition between species, predation and the availability of mates. To explain an effect, identify the biotic factor that has changed, state the direction of change, then trace the consequence through the community. For example, if a new predator arrives, the population of its prey may fall, which reduces competition for the prey's food, so some plant or invertebrate populations may increase, while the predator's own numbers may later fall as prey becomes scarce. If a competitor is removed, the remaining species may expand its niche and increase in number. Always link the changed factor to survival, reproduction and population size, and use the data or context to support each step.
What earns the marks
- Identifies the specific biotic factor that has changed, such as food supply, competition, predation or mate availability.
- States the direction of change and the organism or population affected.
- Explains the consequence for survival or reproduction of the named organism.
- Traces the effect through the community, including at least one further species where the 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, competition, predator and prey.
Common mistakes and how to put them right
Classifying a non-living factor such as temperature as biotic.
Put it right: Check whether the factor is living or was produced by living organisms.
Stopping the explanation after one species.
Put it right: Continue the chain to at least one other population in the community.
Assuming a change always affects only one species.
Put it right: Consider knock-on effects on competitors, prey and predators.
Exam tips
- Identify the biotic factor and the direction of change before writing your chain of reasoning.
- Use because, so and therefore to link each step from factor to population change.
- Refer to the data or context explicitly, quoting a value or trend to support your explanation.
Try the lesson
The start of the Biotic factors: Students should be able to explain how a change in a biotic factor might affect a given community given appropriate data or context. lesson, made from checked teaching notes for this specification point.
Have a go first
In a woodland, the number of rabbits increases because fewer foxes are present. Rabbits eat young tree seedlings. What is likely to happen to the number of tree seedlings in this community?
Listen
Biotic factors are the living influences on a community, including food availability, competition between species, predation and the availability of mates. To explain an effect, identify the biotic factor that has changed, state the direction of change, then trace the consequence through the community. For example, if a new predator arrives, the population of its prey may fall, which reduces competition for the prey's food, so some plant or invertebrate populations may increase, while the predator's own numbers may later fall as prey becomes scarce. If a competitor is removed, the remaining species may expand its niche and increase in number. Always link the changed factor to survival, reproduction and population size, and use the data or context to support each step. A strong answer earns marks for these points. Identifies the specific biotic factor that has changed, such as food supply, competition, predation or mate availability. States the direction of change and the organism or population affected. Explains the consequence for survival or reproduction of the named organism. Traces the effect through the community, including at least one further species where the context allows. A common slip: Classifying a non-living factor such as temperature as biotic. Instead, check whether the factor is living or was produced by living organisms. Exam tip: Identify the biotic factor and the direction of change before writing your chain of reasoning.
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