Which among the following products are produced by cyclic photophosphorylation ?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2)-ATP only
When only PS I is functional, the electron is circulated within the photosystem and the phosphorylation occurs due to cyclic flow of electrons . A possible location where this could be happening is in the stroma lamellae. While the membrane or lamellae of the grana have both PS I and PS II the stroma lamellae membranes lack PS II as well as NADP reductase enzyme. The excited electron does not pass on to NADP+ but is cycled back to the PS I complex through the electron transport chain .
The cyclic flow hence, results only in the synthesis of ATP, but not of NADPH + H+ . Cyclic photophosphorylation also occurs when only light of wavelengths beyond 680 nm are available for excitation.
(Cyclic photophosphorylation)