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chapter 3 biology

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Biosphere
the regions of the surface and atmosphere of the Earth (or other planet) where living organisms exist
population
a group of organisms of the same species populating a given area
species
(biology) taxonomic group whose members can interbreed
community
(ecology) a group of interdependent organisms inhabiting the same region and interacting with each other
ecology
the branch of biology concerned with the relations between organisms and their environment
ecosystem
a system formed by the interaction of a community of organisms with their physical environment
biome
group of ecosystems that have the same climate and dominant communities
biotoc factor
biological influence on organisms within an ecosystem
abiotic factor
physical, or nonliving, factor that shapes an ecosystem
autotroph
plant capable of synthesizing its own food from simple organic substances
primary producer
Organisms that produce energy available for other organisms to eat
Photosynthesis
synthesis of compounds with the aid of radiant energy (especially in plants)
Chemosynthesis
synthesis of carbohydrate from carbon dioxide and water
Heterotroph
an organism that depends on complex organic substances for nutrition
Scavenger
any animal that feeds on refuse and other decaying organic matter
Omnivore
a person who eats all kinds of foods
Decomposers
organisms that break down wastes and dead organisms and return raw materials to the environment
Detritivore
organism that feeds on plant and animal remains and other dead matter
Food chain
(ecology) a community of organisms where each member is eaten in turn by another member
Photoplankton
small photosynthetic organisms found near the surface of the ocean
Food web
(ecology) a community of organisms where there are several interrelated food chains
Zooplankton
animal constituent of plankton
Trophic level
each step in a food chain or food web
Ecological pyramid
diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web
Biomass
the total mass of living matter in a given unit area
Biogeochemical cycle
process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another
Nutrient
any substance that can be metabolized by an organism to give energy and build tissue
Nitrogen fixation
process in which bacteria convert nitrogen gas into nitrogen compounds plants can use to make proteins
Denitrification
conversion of nitrates into nitrogen gas
Limiting nutrient
single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem