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the part of the Earth, including air, land, surface rocks, and water, within which life occurs, and which biotic processes in turn alter or transform
a natural unit consisting of all plants, animals and micro-organisms in an area functioning together with all of the non-living physical factors of the environment
Living and nonliving organic molecules
a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds
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