Populations, communities and ecosystemsSpec B16.1.1
In short
A population is one species in an area; a community is all the populations in an ecosystem; an ecosystem is the community and its environment interacting.
- Population
- A group of organisms of one species, living in the same area, at the same time.
- Community
- All of the populations of different species in an ecosystem.
- Ecosystem
- A unit containing the community of organisms and their environment, interacting together.
| Level | Meaning | Pond example |
|---|---|---|
| Organism | A single living thing | One frog |
| Population | One species, in the same area, at the same time | All the frogs in the pond |
| Community | All the populations of different species in the ecosystem | All the plants, animals and microorganisms in the pond |
| Ecosystem | The community and its environment, interacting together | The pond community plus the water, light and temperature |
(opens full size in a new tab)Quick check
Define a population.
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A group of organisms of one species, living in the same area, at the same time.
Define a community.
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All of the populations of different species in an ecosystem.
Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026