| A | B |
|---|
| carrying capacity | The largest population that an area can support |
| estimate | An approximation of a number, based on reasonable assumptions |
| birth rate | The number of births in a population in a certain amount of time |
| death rate | The number of deaths in a population in a certain amount of time |
| immigration | Moving into a population |
| emigration | Leaving a population |
| population density | The number of individuals in a specific area |
| limiting factor | An environmental factor that causes a population to decrease |
| habitat | An environment that provides the things an organism needs to live, grow, and reproduce |
| biotic factor | A living part of an organism’s habitat |
| abiotic factor | A nonliving part of an organism’s habitat |
| species | A group of organisms that are physically similar and can mate with each other and produce offspring that can also mate and reproduce. |
| population | All the members of one species in a particular area |
| community | All the different populations that live together in an area |
| ecosystem | The community of organisms that live in a particular area along with their nonliving surroundings |
| ecology | The study of how living things interact with each other and their environment |
| organism | a living thing |
| photosynthesis | process some organisms use to make food from sunlight, water and carbon dioxide |
| natural selection | a process by which characteristics that make an individual better suited to its environment become more common in a species |
| adaptation | a behavior or physical characteristic that allows an organism to live successfully in its environment |
| niche | the role of an organism in its habitat, or how it makes its living |
| competition | the struggle between organisms to survive as they attempt to use the same limited resource |
| 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 |
| 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 |
| commensalism | a relationship between two species in which one species benefits and the other is neither helped nor harmed |
| parasitism | a relationship in which one organism lives on or in a host and harms it |
| parasite | the organism that benefits by living on or in a host in a parasitism interaction |
| host | the organism that a parasite lives in or on in a parasitism interaction |
| succession | the series of predictable changes that occur in a community over time |
| primary succession | the series of changes that occur in an area where no soil or organisms exist |
| pioneer species | the first species to populate an area |
| secondary succession | the series of changes that occur in an area where the ecosystem has been disturbed, but where soil and organisms still exist |
