| Term | Definition |
| adaptation | how certain organisms can adapt to their environment |
| autotroph | an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide |
| biology | the study of living organisms |
| cell | the smallest structural and functional unit of an |
| cellular respiration | of, relating to, or consisting of living cells |
| community | a group of interdependent organisms of different species growing or living together in a specified habitat |
| development | a specified state of growth or advancement |
| heterotroph | an organism deriving its nutritional requirements from complex organic substances |
| host | an animal or plant on or in which a parasite or commensal organism lives |
| organ | a part of an organism that is typically self-contained and has a specific vital function, such as the heart or liver in humans |
| organ system | a department or organization that performs a specified |
| organism | an individual animal, plant, or single-celled life form |
| parasite | an organism that lives in or on another organism |