| A | B |
|---|
| ecology | scientific study of interactions between organisms and their environments |
| biosphere | portion of the Earth that supports life; extends from high in atmosphere to bottom of ocean |
| abiotic factor | nonliving parts of an organisms environment |
| biotic factor | all the living organisms that inhabit an environment |
| population | group of organisms all of the same species that interbreed and live at the same place at the same time |
| biological community | a community made up of interacting populations in a certain area at a certain time |
| ecosystem | interactions among populations in a community; the community's physical surroundings or abiotic factors |
| habitat | place where organisms live out their life |
| niche | role or position a species has in its environment; includes bioitic and abiotic interaction as an animal meets it needs for survival and reproduction |
| symbiosis | permanant, close association between two or more organisms of a different species |
| commensalism | sybiotic relationship in which one species benefits and the other is neither harmed nor benefitted |
| mutualism | a sybiotic relationship in which both species benefit |
| parasitism | symbiotic relationship in which one organism benefits at the expense of another; usually another species |
| pioneer species | the first species to take hold in a barren area |
| autotroph | organisms that uses energy from the sun or energy stored in chemical compounds to manufacture their own nutrients |
| biomass | the total mass or weight of all living matter in a given area |
| decomposer | organisms such as fungi and bacteria that breakdown and absorb nutrients from dead organisms |
| food chain | simple model that shows how matter and enery move through an ecosystem |
| food web | model that shows all the possible feeding relationships at each trophic level in a community |
| heterotroph | organism that cannot make its own food and must feed on other organisms for energy and nutrients |
| trophic level | organism that represents a feeding step in the movement of energy and materials through an ecosystem |
| limiting factor | any biotic or abiotic factor that restricts the existence, number or reproduction or distribution of organisms |
| primary succession | colonization of barren land by pioneer species |
| secondary succession | sequence of changes that take place after a community is disrupted by natural disasters or human actions |
