| Term | Definition |
|---|---|
| Abiotic | An environmental factor that is not associated with the activities of living organisms. |
| biogeochemical cycle | |
| biotic | An environmental factor that is associated with or results from the activities of living organisms. |
| carbon cycle | The movement of carbon from the nonliving environment into living things and back. |
| commensalism | A relationship between two organisms in which one organism benefits and the other is unaffected. |
| competition | Ecological relationship in which two or more organisms depend on the same limited resource. |
| Consumer | An organism that eats other organisms or organic matter. |
| decomposer | An organism that gets energy by breaking down the remains of dead organisms or animal wastes and consuming or absorbing the nutrients. |
| ecology | The study of the interactions of living organisms with one another and with their environment. |
| ecosystem | A community of organisms and their abiotic, or nonliving, environment. |
| energy pyramid | A triangular diagram that shows an ecosystem's loss of energy, which results as energy passes through the ecosystem's food chain; each row in the pyramid represents a trophic feeding level in an ecosystem, and the area of a row represents the energy store |
| food chain | The pathway of energy transfer through various stages as a result of the feeding patterns of a series of organisms. |
| food web | A diagram that shows the feeding relationships between organisms in an ecosystem. |
| limiting factor | An environmental factor that prevents an organism or population from reaching its full potential of size or activity. |
| mutualism | A relationship between two species in which both species benefit. |
| parasite | |
| parasitism | A relationship between two species in which one species, the parasite, benefits from the other species, the host, which is harmed. |
| predation | |
| predator | An organism that kills and eats all or part of another organism. |
| prey | An organism that is killed and eaten by another organism. |
| primary consumer | |
| producer | An organism that can make its own food by using energy from its surroundings. |
| secondary consumer | |
| symbiosis | A relationship in which two different organisms live in close association with each other. |
| tertiary consumer | |
| trophic level | |
| water cycle | The continuous movement of water between the atmosphere, the land, the oceans, and living things. |
