| A | B |
|---|
| cell | basic unit of living things |
| tissue | group of similar cells that perform a particular function |
| organ | group of tissues that work together to perform closely related functions |
| organ system | group of organs that work together to perform a specific function |
| cell specialization | the process in which cells develop in different ways to perform different tasks |
| unicellular organism | living thing made of only one cell |
| multicellular organism | living thing made of more than one cell |
| levels of organization | cell, tissue, organ, organ system |
