This document defines key terms used in ecology, including abiotic and biotic factors, niche, habitat, population, community, species, and ecosystem. It explains that ecology is the study of living organisms and their environments, which contain both abiotic non-living factors and biotic living factors. It also distinguishes between a species, which is a group of similar organisms capable of interbreeding, and a population, which is members of a species living in a particular habitat. Finally, it defines a community as interacting populations in a habitat, and an ecosystem as a community interacting with its environment.

1. LIVING ORGANISMS IN
THE ENVIRONMENT
ECOLOGY

2. OBJECTIVES
Syllabus objective 2.2
At the end of this session, you should
be able to distinguish between the
following pairs of terms:
(a) abiotic and biotic factors,
(b) niche and habitat,
(c) population and community,
(d) species and population

3. Ecology:
the study of living organisms in
their environment.

4. Environment:
the abiotic (non-living,
chemical and physical)
and biotic (living)
factors.

5. Species:
A group of individuals
of common ancestry
that closely resemble
each other and are
normally capable of
interbreeding to
produce a fertile
offspring.

6. Population:
Members of a particular
species living in a
particular habitat.

7. Community:
All the populations of
different species
interacting with each
other in a particular
habitat.

8. Ecosystem:
A community of living
organisms (biotic) sharing
and interacting with the
abiotic factors within an
environment.

9. Habitat:
The place where a
particular organism lives.

10. Niche:
The role of an organism in
an ecosystem.