| A | B |
|---|
| ecology | scientific study of all of the interrelationships between organisms and their environment |
| biosphere | the portion of Earth and its atmosphere that supports life |
| biotic factors | the living factors in an organism's environment |
| abiotic factors | the nonliving factors in an organism's environment |
| population | group of organisms of a single species that share the same geographic location at the same time |
| biological community | all the interacting populations that occupy the same geographic area at the same time |
| ecosystem | a biological commuunity and all of the biotic and abiotic factors that affect it |
| biome | a large group of ecosystems that share the same climate and have similar types of communities |
| habitat | where an organism lives |
| niche | a role or position that an organism has in its environment |
| predation | the act of one organism consuming an other organism for food |
| symbiosis | the close relationship that forms when two or more species live together |
| mutualism | a relationship between two or more organisms that live closely together and benefit from each other |
| commensalism | a symbiotic relationship where one organism benefits and the other is neither hurt nor helped |
| parasitism | a relationship where one organism benefits at the expense of another |
| autotroph | an organism that collects energy from sunlight or inorganic substances to produce food (also called producer) |
| heterotroph | an organism that gets its energy requirements from consuming other organisms (also called consumer) |
| herbivore | a heterotroph that only eats plants |
| carnivore | a heterotroph that preys on other heterotrophs |
| omnivore | a heterotroph that eats both plants and animals |
| detritivore | an organism which eat fragments of dead matter in an ecosystem and returns nutrients to the environment |
| trophic level | step in a food chain or web |
| food chain | a simple model that shows how energy flows through an ecosystem |
| food web | a model representing the many interconnected food chains and pathyways in which energy flows through a group of organisms |
| biomass | the total mass of living matter at a trophic level |
| matter | anything that has mass and takes up space |
| nutrient | a chemical substance that an organism must obtain from its environment |
| biogeochemical cycle | the exchange of matter through the biosphere |
| nitrogen fixation | the process of capturing and converting nitrogen into a form that is usable by plants |
| denitrification | the conversion by bacteria of fixed nitrogen compounds to nitrogen gas |
