Q23.The rate of oxygen production is enhanced when there is operation of
(A) Cyclic photophosphorylation
(B) Non-Cyclic photophosphorylation
(C) Both Cyclic and Non-cyclic photophosphorylation
(D) Oxidative phosphorylation
The correct answer is (B) Non-Cyclic photophosphorylation. Non-cyclic photophosphorylation involves both photosystems I and II, where water splitting (photolysis) releases oxygen as a byproduct, directly enhancing oxygen production rates.
This process generates both ATP and NADPH while evolving O₂, unlike other pathways.
Option Analysis
Cyclic photophosphorylation: Involves only photosystem I, with electrons cycling back to produce ATP but no NADPH or oxygen evolution, as water photolysis doesn’t occur.
Non-Cyclic photophosphorylation: Uses both photosystems I and II; electrons from water pass linearly through the chain, producing ATP, NADPH, and oxygen via PSII-mediated water splitting.
Both Cyclic and Non-cyclic photophosphorylation: Cyclic contributes no oxygen, so combining doesn’t enhance O₂ production beyond non-cyclic alone.
Oxidative phosphorylation: Mitochondrial ATP synthesis via electron transport; consumes oxygen as the terminal acceptor, not producing it.
Non-cyclic photophosphorylation enhances the rate of oxygen production through water photolysis at photosystem II, making it essential for atmospheric O₂ generation. This light-dependent reaction powers photosynthesis globally.
Process Details
Cyclic photophosphorylation cycles electrons around PSI for ATP only—no O₂ released. Non-cyclic photophosphorylation drives linear flow, splitting H₂O to yield O₂, ATP, and NADPH. Oxidative phosphorylation occurs in respiration, reducing O₂.
