NEET 2021 Botany Question 144 Solution

When light of wavelength beyond $680\text{ nm}$ is available, or when stroma lamellae lack PS II and NADP reductase, only Photosystem I ($P_{700}$) operates in a closed cycle:

- Non-cyclic photophosphorylation (Z-scheme): Involves both Photosystems II ($P_{680}$) and I ($P_{700}$) operating in series, generating both ATP and $NADPH + H^+$, with photolysis of water. - Cyclic photophosphorylation: Involves only PS I. Electrons cycle back to the reaction center, synthesizing solely ATP without $NADPH$ production or water splitting.

Statement (4) asserts that "cyclic photophosphorylation involves both PS I and PS II". This is incorrect because PS II does not participate in cyclic electron flow.