AQA · GCSE · Combined Science

Course version: 8464 · Version from Sept 2018

Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem

Q: How do I revise Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem for GCSE?

Read the notes on Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem, then test yourself without looking. Answering questions and checking what you missed builds recall faster than re-reading.

Q: Is this Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem guide aligned to the AQA specification?

Yes. This guide is linked to the Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem topic in the AQA GCSE specification.

Ecology studies life at several nested levels.

2 key terms

Study notes

From the checked teaching notes for this specification point.

The idea

Ecology studies life at several nested levels. An individual organism is one member of a species, such as a single oak tree. A population is all the individuals of that species in a habitat. A community is all the populations of different species living together, for example the oaks, insects, fungi and birds in a wood. The community plus the non-living conditions, such as light, water, temperature and soil, forms the ecosystem. The whole ecosystem is therefore the largest level, including living organisms and their physical surroundings interacting together. Moving up each level adds something: more individuals, then more species, then the abiotic environment. Being able to place examples at the correct level is the key skill, and questions often ask you to identify or order these levels.

What earns the marks

An individual organism is a single member of a species, for example one dandelion plant.
A population is all the organisms of one species in a habitat, for example all the dandelions in a field.
A community is all the populations of different species living and interacting in a habitat.
An ecosystem is the community plus the non-living (abiotic) conditions, such as light intensity, temperature, water and soil.
The levels form a sequence of increasing inclusiveness: individual → population → community → ecosystem.
Correct use of the terms population, community and ecosystem when describing a named habitat.

Common mistakes and how to put them right

Calling a group of different species a population.
Put it right: A population contains only one species, while a community contains many species.
Describing an ecosystem as only the living organisms.
Put it right: An ecosystem includes the abiotic conditions as well as the community.
Confusing a habitat with an ecosystem.
Put it right: A habitat is the place where organisms live, whereas an ecosystem includes the community and its physical environment.

Exam tips

Learn the sequence individual → population → community → ecosystem and practise placing unfamiliar examples into it.
When a question gives a named habitat, name a real organism at each level to show the difference clearly.
Read the command word: 'describe' needs the levels in order, while 'explain' needs a reason why each level includes the one below.

Try the lesson

The start of the Communities: different levels of organisation in an ecosystem from individual organisms to the whole ecosystem lesson, made from checked teaching notes for this specification point.

Have a go first

Which level of organisation in an ecosystem is made up of all the organisms of one species living in the same area?

Tip: press 1 to 4 to choose

See it

A vertical flowchart with four boxes connected by downward arrows. The top box is labelled 'Individual organism' and points down to 'Population', which points down to 'Community', which points down to 'Ecosystem' at the bottom. This shows the order of levels from smallest to largest, each level including the one above it. — It shows the sequence of increasing inclusiveness from an individual organism through population and community to the whole ecosystem.

Put it in order

Put these steps in the order they happen.

1. Population
2. Community
3. Ecosystem
4. Individual organism

Key words

Say what each word means before you turn the card.

Levels of ecological organisation

Try answering aloud or in your head before turning the card.

Populations and communities

Try answering aloud or in your head before turning the card.

See every definition

Levels of ecological organisation: The sequence of increasing inclusiveness from individual organism to population to community to ecosystem.
Populations and communities: A population is all the organisms of one species in a habitat, while a community is all the populations of different species living and interacting in a habitat.

Label the diagram

Some boxes have lost their names. Pick the right name for each number.

The diagram again, with 2 boxes numbered instead of named. A vertical flowchart with four boxes connected by downward arrows. The top box is labelled 'Individual organism' and points down to 'Population', which points down to 'Community', which points down to 'Ecosystem' at the bottom. This shows the order of levels from smallest to largest, each level including the one above it.

1Box 1
2Box 2

0 of 2 labelled

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