| Term | Definition |
| ecology | the scientific study of interations among organisms and their environment |
| abiotic factor | physical, or nonliving, factor that shapes an ecosystem |
| biotic factor | biological influence on onganisms within an ecosystem |
| species | group of similar organisms that can breed and produce fertile offspring |
| population | a group of individauls of the same species that live in the same area |
| community | assemblage of different populations that live together in a deffined area |
| ecosystem | collection of all the orgainisms that live in a particular place, together with their nonliving environment |
| biosphere | part of the earth in which life exists including land water, and air or atmosphere |
| autotrophs | organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorgainic compounds; also called a producer |
| heterotroph | organism that obtains energy from the foods it consumes; also called a consumer |
| trophic level | step in a food chain or food web |