| A | B |
|---|
| ecology | study of how living things relate to each other and to their environment |
| mutualism | relationship between organisms in which both organisms benefit |
| food web | network of interconnected food chains |
| commensalism | relationship between organisms in which one organism benefits and the other is neither harmed nor benefited |
| biosphere | layer of Earth that supports life |
| scavenger | feeds on dead organisms |
| food chain | simple model for showing how matter and energy move through an ecosystem |
| biological community | group formed by several populations |
| autotroph | manufactures food using energy from the sun or from chemical compounds |
| parasitism | relationship between organisms in which one organism benefits at the expense of another |
| habitat | place where an organism spends its life |
| trophic level | step in the passage of energy and matter through an ecosystem |
| heterotroph | obtains energy and nutrients from autotrophs |
| decomposer | breaks down dead organisms |
