Question
Cyclic-photophosphorylation results in the formation of
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NADPH
-
ATP and NADPH
-
ATP, NADPH and O2
-
ATP
Solution
D.
ATP
Cyclic-photophosphorylation involves only pigment system-I. When the photons activate PS-I, a pair of the electron are raised to a higher energy level. They are captured by the primary acceptor, which passes them on to ferredoxin, plastoquinone, cytochrome complex, plastocyanin and finally back to reaction centre of PS-I ie, P700. At each step of electron transfer, the electrons lose potential energy. Their trip downhill is caused by the transport chain to pump H+ across the thylakoid membrane. The proton gradient thus established is responsible for forming ATP ( 2 molecules). No reaction of NADP to NADPH + H+.
