| A | B |
|---|
| birth rate | The number of births in a population in a certain amount of time. |
| carrying capacity | The largest population that an area can support. |
| emigration | Leaving a population. |
| death rate | The number of deaths in a population in a certain amount of time. |
| immigration | Moving into a population. |
| limiting factor | An environmental factor that causes a population to decrease. |
| population density | The number of individuals ion an area of a specific size. |
| natural selection | A process by which characteristics that make an individual better suited to its environment become more common in a species. |
| niche | The role of an organism in its habitat, or how it makes its living. |
| parasite | The organism that benefits by living on or in a host in a parasitism interaction. |
| parasitism | A relationship in which one organism lives on or in a host and harms it. |
| symbiosis | A close relationship between two species that benefits at least one of the species. |
| mutualism | A relationship between two species in which both species benefit. |
| predation | An interaction in which one organism kills another for food. |
| predator | The organism that does the killing in a predation interaction. |
| prey | An organism that is killed and eaten by another organism. |
| adaptation | A behavior or physical characteristic that allows an organism to live successfully in its environment. |
| commensalism | A relationship between two species in which one species benefits and the other is neither helped nor harmed. |
| competition | The struggle between organism to survive as they attempt to use the same limited resource. |
| host | The organism that a parasite lives in or on in a parasitism interaction. |
