| A | B |
|---|
| organism | any living thing |
| habitat | an environment that provides the things the organism needs to live, grow, and reproduce |
| biotic factors | the living parts of a habitat |
| abiotic factors | the nonliving parts of and organism's habitat |
| photosynthesis | a process by which producers use water, carbon dioxide and sunlight to make their own food |
| species | a group of organisms that is physically similar and can mate with each other and produce fertile offspring |
| 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 environmentt |
| estimate | an approximate 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 an area of a specific size |
| limiting factors | environmental factors that cause a population to decrease |
| carrying capacity | the largest population that an area can support |
| natural selection | process by which organisms that are better suited to their environment will survive and reproduce |
| adaptation | characteristics that make an individual better suited to its environment |
| niche | the role of an organism in its habitat |
| competition | struggle between organisms to survive as they attempt to use the same limited resources |
| predation | an interaction in which one organism eats another for food |
| predator | organism that does the killing |
| prey | the organism that is killed |
| symbiosis | a close relationship between two species that benefits at least one of the species |
| mutualism | a relationship where both species benefit |
| commensalism | a relationship where one species benefits and the other is neither helped or harmed |
| parasitism | one organism lives on or in another organism harming it |
| parasite | an organism that lives on or in another |
| host | an organism a parasite lives on or in |
| succession | a series of predictable changes that occurs in a community over time |
| primary succession | a series of changes that occur in an area where no soil or organisms exist |
| pioneer species | 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 |
