Question

Cyclic photophosphorylation produces
a. NADPH
b. ATP and NADPH
c. ATP, NADPH and $O_2$
d. APT only

Answer 1

In Cyclic photophosphorylation, photosystem-I (PS-1) is involved in which electron produced moves in a cyclic pathway and is involved in different conversations. ATP is produced by this process and photolysis of water is involved.

Complete answer:
Cyclic photophosphorylation is the process of synthesis of ATP coupled with electron transport chain which is activated by the photosystem-I (PS-I) with long wavelength light that is 700 nm. This process is not affected by any components of PS-II like inhibitors present in PS-II that is, CMU, DCMU and orthophenanthroline.

In this process chlorophyll ‘a’ which is light activated is used to reduce an acceptor and then the electron transport chain brings down the electrochemical gradient through electron carriers to the oxidizing site of PS-I.

ATP production is associated with this electron transport chain. ADP gets converted into ATP in this cycle. In cyclic photophosphorylation, the electrons present in the electron transport chain are transferred back to P700 or chlorophyll ‘a’ rather than going into the NADP from the electron acceptor.

Thus, we can conclude that in the Cyclic photophosphorylation process only ATP will be formed, as electrons do not go to NADP so NADPH and $O_2$ is not produced.

Thus, we can conclude that the Cyclic photophosphorylation process will produce only ATP not NADPH and $O_2$.
Hence, the correct answer is option (B).

Note: Plants undergo two processes that are cyclic photophosphorylation and non-cyclic photophosphorylation. In cyclic photophosphorylation only ATP are produced and in non-cyclic photophosphorylation ATP, NADPH and $O_2$ are produced.