Advertisement Upgrade to remove ads


an organism's environment

Biotic Factors

parts of the habitat that are living

Abiotic Factors

parts of the habitat that are non-living


a group of organisms that can mate with each other and produce fertile offspring


all the members of one species living in a particular area


all the different populations that live together in an area


the community of organisms that live in a particular area along with their nonliving environment


the study of how organisms interact with each other and with their environment

Birth rate

the number of births per 1,000 individuals

Death Rate

the number of deaths per 1,000 individuals


when individuals move into a population


when individuals move out of a population

Population density

the number of individuals in an area of specific size

Limiting factor

an environmental factor that causes a population to stop growing or decrease in size

Carrying capacity

largest population that an area can support

Natural selection

Individuals whose unique characteristics are well suited for an environment tend to survive and produce more offspring. Those unique characteristics are called adaptations.


the role of an organism in its habitat


the struggle between organism to survive as they attempt to use the same limited resources


when an organism kills another one for food or nutrients


the organism that does the killing


the animal that is killed


any relationship in which two species live closely together and at least one of the species benefits


a relationship where both species benefit


a relationship in which one species benefits and the other species is neither helped nor harmed


a relationship that involves one organism living with, on, or inside another organism and harming it

Primary succession

the series of changes that occurs 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 occurs in an area where the ecosystem has been disturbed, but where soil and organisms still exist

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording