| Term | Definition |
|---|---|
| cells | Cells are the basic units of structure and function in living things. |
| cell theory | A widely accepted explanation of the relationship between cells and living things. |
| unicellular | Made of a single cell |
| multicelular | Consisting of multiple cells |
| tissue | A group of similar cells that perform the same function |
| organ | A structure in the body composed of different kinds of tissue. |
| organ system | a group of organs that work together to preform a major function in the body. |
