| Term | Definition |
| ecology | the scientific study of interactions among organism and between organisms and their environment |
| biosphere | the part of Earth where life exists including land, water, and air or atmosphere |
| species | group of similar organisms that can breed and produce fertile offspring |
| population | group of individuals of the same species that live in the same area |
| community | assemblage of different populations that live togeter in a defined area |
| ecosystem | collection of all the organisms that live in a particular place, together with their nonliving environment |
| biome | group of ecosystems that have the same climate and dominant communities |