| A | B |
|---|
| Atoms | The basic unit of matter. |
| Cells | The basic units of structure and function in all living things. Living things are made of these. |
| Molecules | Chemical substances made of two or more atoms that are bonded together by covalent (shared) bonds. |
| Organelles | The membrane bound structures within cells that carry out specialized functions. |
| Ecology | The study of how living things interact with other living things and the physical conditions of their environment. |
| Tissue | A group of cells working together. |
| Organ | A group of tissues working together. |
| Organ Systems | A group of organs working together. |
| Population | The total number of individuals of a particular species living in a particular place. |
| Organism | A whole, complete individual capable of carrying out life functions on its own. |
| Community | Different populations that live together in a defined area. |
| Biome | Group of ecosystems that have the same climate and vegetation |
| Biosphere | The sum of all the ecosystems on earth, or the "sphere" around earth in which life naturally exists. |
| Ecosystem | A community of living things plus the physical conditions in which that community lives. |
