| Term | Definition |
| biosphere | the thin layer of earth, water, and air that supports life |
| ecosystem | smaller portion of biosphere with a specific climate (living and nonliving) |
| community | consists of all living population in the ecosystem (no nonliving) |
| population | consists of all members of a species living in the community |
| species | one distinct form of life |
| organism | a group of organs working together to provide a specific function or to make an induvidual |
| organ | a group of tissues working together for one specific function |
| tissue | a group of cells working together for one specific function |
| cell | smallest unit of life |
| dna/genes | the molecules that direct all the cells functions... they are not living |