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organism that use energy from the sun or energy stored in chemical compounds to manfacture their own nutrients.


organism that cannot make its own food and must feed on other organisms for energy and nutrients.


organisms, such as fungi and bacteria, that break down and absorb nutrients from dead organisms.

food chain

simple model that shows how matter and energy move through an ecosystem.

trophic level

organism that represents a feeding step in the movement of energy and materials through an ecosystem.

food web

model that shows all the possible feeding relationships at each trophic level in a community.


scientific sudy of interactions between organisms and their environments.


portion of Earth that supports life; extends from high in the atmospphere to the bottom of the oceans.

abiotic factor

nonliving parts of an organism's environment; air currents, temperature, moisture, light, and soil are examples.

biotic factor

all the living organisms that inhabit an environment.


group of organisms all of the same species, which interbreed and live in the same place at the same time.

biological community

a community made up of interacting populations in a certain area at a certain time.


interactions among populations in a community; the community's physical surroundings or abiotic factors.


place where an organism livesout its life.


role or position a species has in its its needs for survival and reproduction.


permanent, close association between two or more organisms of different species.


symbiotic relationship in which one species benefits and the other species is neither harmed nor benefited.


a symbiotic relationship in which both species benefit.


symbiotic relationship in which one organism benefits at the expense of another, usually another species.


the total mass or weight of all living matter in a given area.

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