| A | B |
|---|
| stimulus | anything that causes a reaction or change in an organism or any part of an organism |
| hibernation | a period of inactivity and lowered body temperature that some animals undergo in winter as a protection against cold weather and lack of food |
| response | any biological reaction or behavior resulting from the application of a stimulus |
| tropism | growth of all or part of an organism in response to an eternal organism in response to an external stimulus, such as light |
| behavior | an action that an individual carries out in response to a stimulus or to the environment |
| homeostasis | the maintenance of a constant internal state in a changing environment |
| taxis | the movement of a free moving organism or cell in a response to an external stimulus, such as light |
| hormone | a substance that is made in one cell or tissue and that causes a change in another cell or tissue in a different part of the body |
| species | a group of organisms that are closely related and can mate to produce fertile offspring |
| adaptation | an inherited trait that improves an individuals ability to survive and reproduce in a particular environment |
| artificial selection | the human practice of breeding animals or plants that have certain desired traits |
| population | a group of organisms of the same species that live in a specific geographical area |
| evolution | the process in which inherited characteristics within a population change over generations such that new species sometimes arise |
| variation | the occurrence of hereditary or nonhereditary differences between different individuals of a population |
| natural selection | the proess by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do |
