Which of the following statements is incorrect?
Answer: (B) Cyclic photophosphorylation involves both PS I and PS II.. Cyclic photophosphorylation occurs when only PS I is functional — the electron is circulated within PS I and recycled back through the electron transport chain, producing only ATP.
- A.Grana lamellae have both PS I and PS II
- B.Cyclic photophosphorylation involves both PS I and PS II.✓
- C.Both ATP and NADPH + H+ are synthesized during non-cyclic photophosphorylation.
- D.Stroma lamellae have PS I only and lack NADP reductase
Correct Answer
(B) Cyclic photophosphorylation involves both PS I and PS II.
Solution & Explanation
Cyclic photophosphorylation occurs when only PS I is functional — the electron is circulated within PS I and recycled back through the electron transport chain, producing only ATP. It does NOT involve PS II; only non-cyclic photophosphorylation uses both PS II and PS I. Hence the statement that cyclic photophosphorylation involves both photosystems is the incorrect one. NCERT: Class 11 Ch 11, p.140 [140:015-024]: "When only PS I is functional, the electron is circulated within the photosystem and the phosphorylation occurs due to cyclic flow of electrons"