Assertion : Cyclic photophosphorylation synthesises ATP. Reason : ATP synthesis in cyclic…
Assertion : Cyclic photophosphorylation synthesises ATP.
Reason : ATP synthesis in cyclic photophosphorylation is associated with NADPH formation.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Solution
In case of cyclic photophosphorylation, the electron while passing between ferredoxin and plastoquinone and/or over the cytochrome complex, loses sufficient energy to form ATP from ADP and inorganic phosphate.
In cyclic photophosphorylation no NADPH formation takes place. But in case of noncyclic photophosphorylation, NADP - reduced through $\mathrm{H}^{+}$released during photolysis forms NADPH. ATP synthesis is not direct and the energy released by electron is actually used for pumping $\mathrm{H}^{+}$ions across the thylakoid membrane. It creates a proton gradient. The gradient triggers the coupling factor to synthesise ATP from ADP and inorganic phosphate.