2.1

Organisms and Their Environment

Ecology- branch of biology that studies interactions among organisms and their environment.

Biosphere- portion of earth that supports life

Abiotic factors- nonliving parts of an organisms environment

Biotic factors- all living organisms that inhabit an environment

Levels of organization in Ecology

1. Organism

2. Populations- organisms of one species that interbreed and live in the same place at the same time.

3. Community- collection of interacting populations

4. Ecosystem- interactions of a community and its surrounding abiotic factors. (Terrestrial & Aquatic ecosystems)

Organisms in Ecosystems

Habitat- place where an organisms lives its life

Niche- the role and position a species has in its environment

Living relationships

Predator-Prey

Symbiosis- living together

Commensalism-one species benefits and the other species is neither harmed nor benefitted.

Mutualism- both species benefit

Parasitism- one organism benefits at the expense of the other.