Term | Definition |
ecology | the study of the interactions of living organisms with one another and with their environment |
interdependence | the dependence of every organism on its connections with other living and nonliving parts of its environment |
ecological model | a model that represents or describes the relationship between the components of an ecological system |
biosphere | the part of Earth where life exists; includes all of the living organisms on Earth |
ecosystem | a community of organisms and their abiotic environment |
community | a group of various species that live in the same habitat and interact with each other |
population | a group of organisms of the same species that live in a specific geographical area and interbreed |
habitat | the place where an organism usually lives |
biotic factor | an environmental factor that is associated with or results from the activities of living organisms |
abiotic factor | an environmental factor that is not associated with the activities of living organisms |
tolerance curve | a graph of the performance of an organism versus the value of an environmental variable |
acclimation | an organism's change in response to a change in the organism's environment |
conformer | an organism whose physiological reactions follow environmental changes |
regulator | organisms that use energy to control some of their internal conditions |
dormancy | a state in which seeds, spores, bulbs, and other reproductive organs stop growth and development and reduce their metabolism, especially respiration |
migration | in general, any movement of individuals or populations from one location to another; specifically, a periodic group movement that is characteristic of a given population or species |
niche | the unique position occupied by a species, both in terms of its physical use of its habitat and its function within an ecological community |
generalist | a species that has a broad niche such that the species can tolerate a wide range of conditions and can use a variety of resources |
specialist | an individual or a species that is adapted to a particular environmental factor or ecological niche and that can tolerate only a narrow range of conditions |
producer | an organism that can make organic molecules from inorganic molecules; a photosynthetic or chemosynthetic autotroph that serves as the basic food source in an ecosystem |
chemosynthesis | the production of carbohydrates through the use of energy from inorganic molecules instead of light |
gross primary productivity | the rate at which organic matter is assimilated by plants and other producers during a period of time over a certain area |
biomass | plant material, manure, or any other organic matter that is used as an energy source |
net primary productivity | the rate at which biomass accumulates in an ecosystem |
consumer | an organism that eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources |
herbivore | an organism that eats only plants |
carnivore | an organism that eats animals |
omnivore | an organism that eats both plants and animals |
detritivore | a consumer that feeds on dead plants and animals |
trophic level | one of the steps in a food chain or food pyramid; examples include producers and primary, secondary, and tertiary consumers |
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 |
biogeochemical cycle | the circulation of substances through living organisms from or to the environment |
groundwater | the water that is beneath the Earth's surface |
water cycle | the continuous movement of water between the atmosphere, the land, and the oceans |
transpiration | the process by which plants release water vapor into the air through stomata; also the release of water vapor into the air by other organisms |
carbon cycle | the movement of carbon from the nonliving environment into living things and back |
nitrogen cycle | the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem |
nitrogen fixation | the process by which gaseous nitrogen is converted into ammonia, a compound that organisms can use to make amino acids and other nitrogen-containing organic molecules |
nitrogen-fixing bacteria | bacteria that convert atmospheric nitrogen into ammonia |
ammonification | the formation of ammonia compounds in the soil by the action of bacteria on decaying matter |
nitrification | the process by which nitrites and nitrates are produced by bacteria in the soil |
denitrification | the liberation of nitrogen from nitrogen-containing compounds by bacteria in the soil |
phosphorus cycle | the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment |
decomposer | an organism that feeds by breaking down organic matter from dead organisms; examples include bacteria and fungi |