Cyclic electron flow (CEF) is a crucial component of photosynthesis in both plants and cyanobacteria. The parsing of the proton-motive force between ΔpH and Δψ, regulated in many different ways (cyclic electron flow, ATPsynthase conductivity, ion/H+ transporters), is comprehensively reported. B) It changes the direction of... See full answer below. Differences between the supply of ATP from linear electron transport and an increased demand could be balanced via cyclic electron flow (Kramer and Evans, 2011; Walker et al., 2014; Yamori et al., 2016). The electron transport chain of photosynthesis is initiated by absorption of light by photosystem II (P 68o). Median response time is 34 minutes and may be longer for new subjects. In the thylakoid reactions, electrons excised from water in PSII are transferred to NADP + through the cytochrome b 6 f complex and PSI, resulting in the production of NADPH. A) It requires photosystem II but not Photosystem I. The physiological significance of photosystem I cyclic electron transport has been underestimated, and our knowledge of the machineries involved remains very limited. Recent studies show that the cyclic electron flow can operate under aerobic conditions and support a simple competition model where the excess reducing power is recycled to match the demand for ATP. After absorbing light energy the electrons produces NADPH and accepting donor electrons easily because it is a series process. Three major electron transfer pathways known are linear, cyclic and pseudo-cyclic electron transfer (LEF, CEF and PCEF, respectively). True, cyclic electron transport only uses the P700 photosystem. Photosynthesis consists of a series of electron transport reactions in the thylakoid membrane and carbon fixation reactions in the stroma. *Response times vary by subject and question complexity. Linear electron transport generates both ATP and NADPH, whereas PSI cyclic electron transport produces ATP without producing NADPH. However, up to now, it was not clear how it differs … Cyclic electron transport in photosynthesis is required when the total demand for ATP exceeds the demand for ATP in basic CO 2 fixation reactions. FIGURE 1: Overall reaction of photosynthesis Chemical Equation for photosynthesis process: 6CO 2 + 12H 2 PHOTOSYNTHESIS The conversion of light energy to chemical energy that is stored in sugar or other organic compound using CO 2 and water (occurs in plants, algae & certain unicellular eukaryotes and some prokaryotes). All three pathways are necessary for poised and sustained synthesis of ATP and NADPH and their interplay enables the flexibility of photosynthesis … The light reactions in photosynthesis drive both linear and cyclic electron transport around photosystem I (PSI). Photosynthesis Research 1995 , 46 (1-2) , 277-285. In photosynthesis, the electron transport chain is processed with the help of chlorophyll by absorbing light energy from the sun. PCC 7942. However, recent genetic approaches using Arabidopsis thaliana have clarified the essential functions of this electron flow in both photoprotection and photosynthesis. The light-driven reaction of photosynthesis also called light reaction (Hill reaction), referred to as electron transport chain, were first propounded by Robert Hill in 1939. Light adaptation of cyclic electron transport through Photosystem I in the cyanobacterium Synechococcus sp. Photosynthesis drive both cyclic electron transport support photosynthesis and cyclic electron flow in both photoprotection and photosynthesis and cyclic electron (! It was not clear how it differs … a ) it changes the direction of... 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