| A | B |
|---|
| cell | in biology, the smallest unit that can perform all life processes |
| stimulus | anything that causes a reaction or change in an organism |
| homeostasis | the maintenance of a constant internal state in a changing environment |
| DNA | a molecule that is present in all living cells and that contains the information that determines the traits that a living thing inherits and needs to live |
| sexual reproduction | reproduction in which the sex cells from two parents unite to produce offspring that share traits from both parents |
| asexual reproduction | reproduction that does not involve the union of sex cells and in which one parent produces offspring that are genetically identical to the parent |
| evolution | the process in which inherited characteristics within a population change over generations such that new species sometime arise |
| artificial selection | the human practice of breeding animals or plants that have certain desired traits |
| natural selection | the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well-adapted individuals do |
| variation | the occurence of hereditary or non-hereditary differences between different individuals of a population |
| mutation | a change in the nucleotide base sequence of a gene or DNA molecule |
| adaptation | a characteristic that improves an individual's ability to survive and reproduce in an environment |
| extinction | the death of every member of a species |
