Question

Cyclic photophosphorylation results in the formation of:

• A. ATP
• B. NADPH
• C. ATP and NADPH
• D. ATP, NADPH and $O_2$

Answer 1

The correct option is A ATP

In non-cyclic photophosphorylation, electrons move from PSII to PSI and then to NADP. Thus, the NADP gets reduced to NADPH. In the process of the transport of the electrons, ATP is also formed.
In cyclic photophosphorylation, only PSII is involved. The electrons that are lost by photoexcitation from PSII are cycled back to PSII, instead of being accepted by NADP. Hence, no NADPH is produced. However, since electrons are transported through an electron transport chain, ATP is still formed.
In non-cyclic photophosphorylation, since the electrons are not cycled back to PSII, the gap of electrons in PSII is filled by the oxidation of water, which results in the formation of molecular oxygen. Oxygen gas is not produced in cyclic photophosphorylation.
Hence, during cyclic photophosphorylation, only ATP molecules are generated.