AQA GCSE Biology

Revision Notes

7.1.3 Biotic Factors

Types of Biotic Factors

  • In Biology, ‘biotic’ means living. A biotic factor is a living factor

Biotic factors that can affect a community table

Biotic factors that affect a community table, IGCSE & GCSE Biology revision notes

Effect of Biotic Factors

  • You should be able to extract and interpret information from charts, graphs and tables relating to the effect of biotic factors on organisms within a community


Example exam question

A study recorded the number of red and grey squirrels in a particular woodland habitat for 20 years. Grey squirrels were introduced to the habitat in year 6 of the study.


The relationship between a grey squirrel population and a red squirrel population over time graph, IGCSE & GCSE Biology revision notes

Graph showing the relationship between a grey squirrel population and a red squirrel population over time

What conclusion can you draw from this graph about the effect of introducing grey squirrels to a habitat that is occupied by red squirrels? Explain why this might have occurred.

Example exam answer

As the number of grey squirrels increases, the number of red squirrels decreases. This might have occurred because the two squirrel species are competing for one or more of the same resources. Grey squirrels are better adapted to use these resources and have outcompeted the red squirrels until eventually there are too few red squirrels left to breed successfully and there are none left in the habitat.

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Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.

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