: Phosphorylation takes place in two ways - cyclic and noncyclic. In noncyclic photo- phosphorylation high energy electrons released from P-680 (PSI) do not return to P-680 but pass through pheophytin, plastoquinone, cytochrome b6-f complex, plastocyanin and then enter P-700 and the excited electrons are used in the reduction of NADP to NADPH2 . When the electron from P- 700 is carried by FeS (iron sulphur protein complex), Fd (ferredoxin), is reduced and with the help of Fd-NADP reductase, NADP is reduced to NADPH2 .