B4

Ecosystem

A community of organisms interacting with each other and their physical environment.

Community

All the different populations of species living in the same area.

Habitat

The natural environment where an organism lives.

Population

All the individuals of the same species living in the same area.

Producer

An organism (usually a plant) that makes its own food by photosynthesis.

Consumer

An organism that obtains energy by eating other organisms.

Decomposer

Organism (e.g., bacteria, fungi) that breaks down dead material and recycles nutrients.

Food chain

A diagram showing how energy and nutrients pass from one organism to another.

Food web

A network of interlinked food chains showing many feeding relationships.

Trophic level

A stage in a food chain, e.g., producer, primary consumer, secondary consumer.

Biomass

The total dry mass of living organisms in a given area.

Pyramid of numbers

Diagram showing the number of organisms at each trophic level.

Pyramid of biomass

Diagram showing the mass of organisms at each trophic level; usually pyramid-shaped.

Biodiversity

The variety of living organisms in an ecosystem.

Competition

When organisms fight for the same limited resources (e.g., food, mates, territory).

Interdependence

How organisms rely on each other for survival, e.g., food, shelter, pollination.

Abiotic factor

Non-living factor that affects organisms, e.g., temperature, water, light.

Biotic factor

Living factor that affects organisms, e.g., predation, disease, competition.

Quadrat

A square frame used to sample the abundance of organisms in a habitat.

Transect

A line along which samples are taken to measure changes in organisms across a habitat.

Sampling

The process of studying a small area to estimate conditions in a larger one.

Predator-prey cycle

A repeating pattern where predator and prey populations rise and fall over time.

Adaptation

A feature that helps an organism survive in its environment.

Structural adaptation

A physical feature that helps survival (e.g., thick fur, large leaves).

Behavioural adaptation

A way an organism behaves that helps it survive (e.g., migration, nocturnal activity).

Functional adaptation

Internal body processes that help survival (e.g., producing antifreeze proteins).