| A | B |
|---|
| biosphere | all the parts of the planet that are inhabited by living things; the sum of all earth's ecosystems |
| ecosystem | community of living things plus the nonliving features of the environment that support them |
| organism | living thing |
| cell | basic unit of living matter separated from its environment by a plasma membrane |
| DNA | deoxyribonucleic acid; the chemical responsible for inheritance |
| gene | a unit of inherited information in DNA |
| species | distinct form of life |
| domain | broadest category used to classify life forms |
| unicellular | consisting of a single cell |
| prokaryotic cell | cell lacking a nucleus and most other organelles |
| eukaryotic cell | cell with a nucleus (surrounded by its own membrane) and other internal organelles |
| multicellular | consisting of many cells |
| system | complex organization formed from a simpler combination of parts |
| photosynthesis | process by which plants use the sun's energy to convert water and carbon dioxide into sugar |
| producer | organism that makes its own food (autotroph) and produces organic molecules that serve as food for other organisms in its ecosystem |
| consumer | organism that obtains food by eating producers (autotrophs) or other consumers |
| homeostasis | internal stability or "steady state" maintained by the body |
| adaptation | inherited characteristic that improves an organism's ability to survive and reproduce in a particular environment |
| population | group of individuals of the same species living in a particular area at the same time |
| natural selection | process by which individuals with inherited characteristics well-suited to the environment leave more offspring than do other individuals |
| evolution | generation to generation change in the proportion of different inherited genes in a population that account for all of the changes that have transformed life over an immense time |
