| A | B |
|---|
| atom | smallest unit /building block of matter |
| element | simplest substance that cannot be broken down |
| molecule | two or more atoms chemically combined |
| organism | a living thing |
| organ system | a group of organs that function together to perform a task |
| organ | a group of tissues that function together |
| tissue | a croup of cells that function together |
| cell | basic building block of life |
| organelle | a subunit in the cell that performs a specific task |
