A population is all the organisms of one species in a habitat. Populations of different species form a community. Within a habitat a species occupies a niche governed by adaptation to both biotic and abiotic conditions.

Ecosystem- the biotic and abiotic conditions and relationships with in a community in a given area.

Biotic- living organisms.

Abiotic- physical conditions (e.g. soil PH/temperature)

Ecology- the study of interactions which determine where organisms are, what they do and how many there are.

Habitat- the area in an ecosystem in which an organism lives.

Population- group of individuals of the same species (in the same habitat at the same time).

Community- a collection of populations (in the same habitat at the same time).

Niche- the role that an organism plays in an ecosystem, both in terms of what it brings to and takes from the community.