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Chapter 18


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
Created by: FarlowA20