Question

Which one is produced during cyclic photo-phosphorylation ?

• A. ATP and $ NADP{{H}_{2}} $
• B. ATP only
• C. ATP and $ {{O}_{2}} $
• D. $ NADP{{H}_{2}} $

Answer 1

Answer: (B)

Photophosphorylation is the synthesis of ATP during photosynthesis. It is of two types: (i) Cyclic photophosphorylation: In cyclic photophosphorylation only ATP is produced. It starts with $ {{P}_{700}} $ which being excited releases electrons that are accepted by ferredoxine. The electrons passess through plastoquinone, cyt. $ -{{b}_{6}} $ , cyt.-f and plastocyanin to $ {{P}_{700}} $ . The energy released between cyt. $ -{{b}_{6}} $ and cyt.-f is used to form ATP. (ii) Non-cyclic photophosphorylation: In non-cyclic photophosphorylation electron released from $ {{P}_{680}} $ goes through PS-I and PS-II to $ NAD{{P}^{+}} $ , i.e., ATP and $ NADP{{H}_{2}} $ are formed in non-cyclic photophosphorylation. $ {{O}_{2}} $ is released in PS-II by photolysis of water.