Levels of organisation

Ecosystems and material cycles · Communities and interdependence · note 1 of 4

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Levels of organisationSpec 9.1

In short

The levels of organisation in ecology go from organism to population, community and ecosystem, and each level contains the one before. A population is all the organisms of one species in an area, a community is all the populations of different species there, and an ecosystem is a community together with the non-living (abiotic) parts of its environment.

Living things can be described at different levels of organisation, from a single organism up to a whole ecosystem. Each level contains the one before it.

Levels of organisation in ecology
Level	What it means	Example
Organism	A single living thing	One badger
Population	All the organisms of one species living in the same area	All the badgers in a wood
Community	All the populations of different species living in the same area	The badgers, foxes, oak trees, insects and fungi in the wood
Ecosystem	A community together with the non-living (abiotic) parts of its environment	The wood, including its soil, water, light and temperature

An ecosystem is made of living (biotic) and non-living (abiotic) parts that interact with each other. Energy and materials move between them.

Common mistake:

A population is one species only. If an answer mentions different species living together, it is describing a community.

Nested boxes showing the levels of organisation in a wood: one badger (organism) inside all the badgers (population), inside the community with an oak tree, fungi and an insect, inside the ecosystem with light, temperature, water and soil. — Each level contains the one before it: **organism**, **population**, **community**, then **ecosystem** (the community plus its abiotic parts).

Written and checked against the Edexcel GCSE Combined Science (1SC0) specification · Updated October 2026

Frequently asked questions

What is the difference between a population and a community?

A population is all the organisms of one species living in the same area, such as all the badgers in a wood. A community is all the populations of different species living in the same area. An ecosystem is a community together with the non-living, abiotic parts of its environment, such as soil, water and light.

What are abiotic and biotic factors?

Abiotic factors are non-living factors that affect a community, such as temperature, light, water and pollutants. Biotic factors are living factors, such as competition for food, water, light and space, and predation. A change in either type can change which species live in a community and how many of each there are.

Why does the predator peak come after the prey peak?

The predator peak comes after the prey peak because predator numbers rise only once there is more food. When prey numbers rise, predators have more to eat, so their numbers increase. More predators eat more prey, so prey numbers fall. With less food, predator numbers then fall, and the prey population can recover.

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