C4 pathway

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C4 pathway A pathway of carbon fixation, found most commonly in tropical plants that have high rates of growth and photosynthesis and that are adapted to high temperatures, strong light, low carbon dioxide levels, and low water supply. Its importance lies mainly in its reduction of photorespiration. The first product formed as a result of the carboxylation by CO2 of an acceptor molecule, phospho-enolpyruvate (PEP), is the four-carbon oxalo-acetate (OAA). Eventually the CO2 is handed on to, and refixed by, the Calvin cycle.

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