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carbon fixation is one of three metabolic pathways for carbon fixation in photosynthesis, along with and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into 3-phosphoglycerate through the following reaction: :CO2 + RuBP → (2) 3-phosphoglycerate This reaction occurs in all plants as the first step of the Calvin–Benson cycle. In plants, carbon dioxide is drawn out of malate and into this reaction rather than directly from the air. Plants that survive solely on fixation ( plants) tend to thrive in areas where sunlight intensity is moderate, temperatures are moderate, carbon dioxide concentrations are around 200 ppm or higher,〔C. Michael Hogan. 2011. ("Respiration". ''Encyclopedia of Earth''. Eds. Mark McGinley and C. J. Cleveland. National Council for Science and the Environment. Washington, D.C. )〕 and groundwater is plentiful. The plants, originating during Mesozoic and Paleozoic eras, predate the plants and still represent approximately 95% of Earth's plant biomass. plants lose 97% of the water taken up through their roots to transpiration. Examples include rice and barley. plants cannot grow in hot areas because RuBisCO incorporates more oxygen into RuBP as temperatures increase. This leads to photorespiration, which leads to a net loss of carbon and nitrogen from the plant and can, therefore, limit growth. In dry areas, plants shut their stomata to reduce water loss, but this stops from entering the leaves and, therefore, reduces the concentration of in the leaves. This lowers the :O2 ratio and, therefore, also increases photorespiration. and CAM plants have adaptations that allow them to survive in hot and dry areas, and they can, therefore, out-compete plants in these areas. The isotopic signature of plants shows higher degree of 13C depletion than the plants. ==See also== * C2 photosynthesis 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「C3 carbon fixation」の詳細全文を読む スポンサード リンク
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