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Maize (Zea mays, Poaceae) is the most widely cultivated C 4 plant.[1]In botany, C 4 carbon fixation is one of three known methods of photosynthesis used by plants. C 4 plants increase their photosynthetic efficiency by reducing or suppressing photorespiration, which mainly occurs under low atmospheric CO 2 concentration, high light, high temperature, drought, and salinity.
C 4 plants have a competitive advantage over plants possessing the more common C 3 carbon fixation pathway under conditions of drought, high temperatures, and nitrogen or CO 2 limitation. When grown in the same environment, at 30 °C, C 3 grasses lose approximately 833 molecules of water per CO 2 molecule that is fixed, whereas C 4 grasses lose ...
The adaptations of C4 plants provide an advantage over the C3 pathway, which loses efficiency due to photorespiration. [22] The ratio of photorespiration to photosynthesis in a plant varies with environmental conditions, since decreased CO 2 and elevated O 2 concentrations would increase the efficiency of photorespiration. [20]
The latter occurs not only in plants but also in animals when the carbon and energy from plants is passed through a food chain. The fixation or reduction of carbon dioxide is a process in which carbon dioxide combines with a five-carbon sugar , ribulose 1,5-bisphosphate , to yield two molecules of a three-carbon compound, glycerate 3-phosphate ...
Cyanobacteria such as these carry out photosynthesis. Their emergence foreshadowed the evolution of many photosynthetic plants and oxygenated Earth's atmosphere. Biological carbon fixation, or сarbon assimilation, is the process by which living organisms convert inorganic carbon (particularly carbon dioxide, CO 2) to organic compounds.
Many plants lose much of the remaining energy on growing roots. Most crop plants store ~0.25% to 0.5% of the sunlight in the product (corn kernels, potato starch, etc.). Photosynthesis increases linearly with light intensity at low intensity, but at higher intensity this is no longer the case (see Photosynthesis-irradiance curve). Above about ...
C4 carbon fixation evolved to circumvent photorespiration, but can occur only in certain plants native to very warm or tropical climates—corn, for example. Furthermore, RuBisCOs catalyzing the light-independent reactions of photosynthesis generally exhibit an improved specificity for CO 2 relative to O 2, in order to minimize the oxygenation ...
C4 photosynthesis is estimated to have evolved over 60 times within plants, [228] via multiple different sequences of evolutionary events. [229] C4 plants use a different metabolic pathway to capture carbon dioxide but also have differences in leaf anatomy and cell biology compared to most other plants.