Chapter18

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ECOLOGY

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deals with the relations of organisms to one another and to their physical surroundings

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ecological model

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represent or describe the components of nan ecological system

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ecosystem

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a biological community of interacting organisms and their physical environment

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population

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all members of a species that live in one place at one time

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interdependence

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mutual dependence between things

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biosphere

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the regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms.

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community

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a group of interdependent organisms of different species growing or living together in a specified habitat.

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habitat

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the natural home or environment of an animal, plant, or other organism.

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tolerance curve

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a graph of performance versus values of an environmental variable

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migration

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moving to a new environment during unfavorable conditions

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abiotic factor

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the nonliving things that affect an organism

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dormancy

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a state of reduced activity during unfavorable conditions

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producer

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autotrophs, or organisms that capture energy and use it to make organic molecules

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biomass

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organic material that has been produced in an ecosystem

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chemosynthesis

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a process which some bacteria that are autotrophs but do not preform photosynthesis go through in order to make food by using energy stored in inorganic molecules to produce carbohydrates

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consumers

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organisms that obtain energy by consuming organic molecules made by other organisms

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herbivores

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consumers that eat only producers

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carnivores

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consumers that eat only other consumers

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omnivores

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consumers that eat both producers and other consumers

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detritivore

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detritivores organisms that eat recently dead organisms, fallen leaves, and animal wastes

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decomposers

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detritivores that cause decay by breaking down complex molecules into simpler molecules

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trophic level

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an organism's position in a sequence of energy transfers

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food chain

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a single pathway of feeding relationships among organisms in a ecosystem that results in energy transfer

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food web

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interrelated food chains in an ecosystem

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ground water

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water in the soil or in underground formations of porous rock

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water cycle

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movement of water between various reservoirs

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transpiration

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the process by which water evaporates from the leaves of plants in terrestrial ecosystems

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carbon cycle

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the cycle that photosynthesis and cellular respiration form the basis of

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nitrogen cycle

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the complex pathway that nitrogen follows in an ecosystem

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nitrogen fixation

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the process of converting nitrogen gas to nitrate

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nitrogen-fixing bacteria

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bacteria that live in the soil and inside the swellings on the roots of some kinds of plants that transform nitrogen gas into a usable form

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phosphorous cycle

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the movement of phosphorous from the environment to organisms and then back to the enviroment

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niche

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position or role taken by a kind of organism within its community