| A | B |
|---|
| abiotic factor | nonliving parts of an organism's environment; temperature, moisture, light, and soil are examples |
| biosphere | portion of earth that supports life; extends from the atmosphere to the bottom of the oceans |
| biotic factor | all the living organisms that inhabit an environment |
| commensalism | symbiotic relationship in which one species benefits and the other species is neither harmed nor benefitted |
| community | collection of several interacting populations that inhabit a common environment |
| ecology | scientific study of interactions among organisms and their environment |
| ecosystem | interactions among populations in a community; the community's physical surroundings or abiotic factors |
| habitat | place where an organism lives out its life |
| mutualism | a symbiotic relationship in which both species benefit |
| niche | role and position a species has in its environment |
| parasitism | symbiotic relationship in which one organism benefits at the expense of the other species |
| population | group of organisms of one species that interbreed and live in the same place at the same time |
| symbiosis | permanent, close association between two or more organisms of different species |
| autotroph | organisms that use energy from the sun or energy stored in chemical compounds to make their own nutrients |
| decomposer | organisms such as fungi, that break down and absorb nutrients from dead organisms |
| food chain | simple model that shows how matter and energy move through an ecosystem |
| food web | model that expresses all the possible feeding relationships at each trophic level in a community |
| heterotroph | organisms that can not make their own food and must feed on other organisms for energy and nutrients |
| scavenger | animals that feed on animals that have already died |
| trophic level | organisms in a food chain that represents a feeding step in the passage of energy and materials through an ecosystem |
