Question

Read the following four statements- A, B, C and D and select the right option having both correct statements.
(A) Z scheme of light reaction takes place in presence of PS I only.
(B) Only PS I is functional in cyclic photophosphorylation.
(C) Cyclic photophosphorylation results into synthesis of ATP and NADPH${}_2$.
(D) Stroma lamellae lack PS II as well as NADP.

• A. (B) and (D)
• B. (A) and (B)
• C. (B) and (C)
• D. (C) and (D)

Answer 1

The correct option is A (B) and (D)

Z scheme of light reaction is non cyclic fow of electron from PSII through quinone, cyt $b_6$ f complex and plastocyanin to NADPH via PSI; it does not return to PSII. NADP reductase enzyme is located on stromal side of PSI; Z scheme includes both PSI and PSII. Absence of PS-II leads to non cyclic photophosphorylation in which electrons are passed from PS-I, via electron transfer chain, to back to PS-I with formation of ATP. Cyclic photophosphorylation does not pass electrons to NADP; rather electrons are passed back to PSI. Result is formation of ATP but no NADPH2. Stroma lamellae have PSI only but lack PSII and NADP reductse. Statements B an D are correct. Correct answer is A.