Populations — Cambridge IGCSE Combined Science

What populations, communities and ecosystems are, using a pond as the example.

Spec B16.1Organisms and their environment, subtopic 3 of 3

Revision notes

1 short note, in the order of the specification. Each one in short:

Populations, communities and ecosystems
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.

1 exam-style question (3 marks), each with its mark scheme.

1 card: flip them, mark what you knew, and practise the rest.

The whole of organisms and their environment on one page, so you can see where this subtopic fits.

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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