GCSEBiologyAQARevision NotesEcologyAdaptations, Interdependence & CompetitionAbiotic Factors

Abiotic Factors (AQA GCSE Biology): Revision Note

Exam code: 8461

Written by: Lára Marie McIvor

Reviewed by: Dr Natalie Lawrence

Updated on 2 September 2026

Types of abiotic factors

In biology, ‘abiotic’ means non-living. An abiotic factor is a non-living factor
Some abiotic factors which can affect a community are shown in the table below:

Abiotic factors that affect a community

Light intensity: light is needed by plants for photosynthesis. More light leads to an increase in rate of photosynthesis and an increase in plant growth rate
Temperature: affects the rate of photosynthesis in plants
Moisture levels: plants and animals require water to survive
Soil pH and mineral content: different species of plants are adapted to different soil pH levels and nutrient concentration levels
Wind intensity and direction: wind speed affects transpiration rate in plants. Transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves
Carbon dioxide levels for plants: CO₂ is required for photosynthesis in plants. CO₂ concentration affects the rate of photosynthesis
Oxygen levels for aquatic animals: some aquatic animals (such as fish) can only survive in water with high oxygen concentrations

Effect of abiotic factors

Exam questions can ask students to extract and interpret information from charts, graphs and tables relating to the effect of abiotic factors on organisms within a community

Worked Example

Plants of the same species were grown in tanks with different CO₂ levels. Their height was measured after 3 weeks and an average taken:

Bar chart showing the effect of carbon dioxide concentration on average plant height. The x-axis shows CO₂ concentration from 5% to 30%, and the y-axis shows average height of plants in cm. Average plant height increases from 10 cm at 5% CO₂ to 20 cm at 10%, 30 cm at 15%, 40 cm at 20%, 50 cm at 25% and 60 cm at 30%. — **Effect of carbon dioxide concentration on average plant height**

Use this image

What conclusion can you draw from this graph about the effect of CO₂ concentration on plant growth rate?

Explain your answer.

[3 marks]

Answer:

As CO₂ concentration increases, average plant height also increases. For example, at 5% CO₂, average plant height was 10 cm, but at 30% CO₂, average plant height was 60 cm. This shows that the higher the CO₂ concentration, the greater the plant growth rate. This is because CO₂ is used by plants for photosynthesis, which allows the plant to produce glucose for energy to grow.

Examiner Tips and Tricks

When answering questions that refer to a chart, graph or table, remember to reference specific figures from the data to support your answer, as seen in the example above.

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