| Term | Definition |
| tissue | a group of similar cells that work together to perform a specific job in the body |
| organ | a combination of two or more tissues that work together to perform a specific function |
| organ system | a group of organs working together to perform body functions |
| organism | anything that can independently carry out life processes |
| unicellular | made of a single cell |
| multicellular | made of many cells |
| population | a group of individuals of the same species that live together in the same area at the same time |
| community | all of the populations of different species that live and interact in an area |
| ecosystem | a community of organisms and their non-living environment |
| heart, leaf, stomach | examples of organs |
| skin | the largest organ in your body |
| cell | the basic unit of living things |