Question

Non-cyclic photophosphorylation involves unidirectional flow of electrons from ___________.

• A. PS-II $\rightarrow$ cytochromes $\rightarrow$ PS-I $\rightarrow$ NADP $\rightarrow$ photolysed water
• B. PS-II $\rightarrow$ PS-I $\rightarrow$ NADP $\rightarrow$ photolysed water
• C. Photolysed water $\rightarrow$ PS-II $\rightarrow$ cytochromes $\rightarrow$ PS-I $\rightarrow$ NADP
• D. Photolysed water $\rightarrow$ PS-I $\rightarrow$ PS-II $\rightarrow$ NADP

Hint:

Non-cyclic photophosphorylation produces ATP, NADPH, and oxygen.

Answer 1

The Correct Option is C

Step 1: Understanding non-cyclic photophosphorylation.
Non-cyclic photophosphorylation occurs in the thylakoid membrane and involves both PS-II and PS-I.
Step 2: Direction of electron flow.
Electrons originate from photolysis of water, move through PS-II, cytochrome complex, PS-I, and finally reduce NADP to NADPH.
Step 3: Analysis of options.
(A), (B), (D): Incorrect electron flow sequence.
(C): Correct sequence of electron transport.
Step 4: Conclusion.
The correct unidirectional flow is Photolysed water $\rightarrow$ PS-II $\rightarrow$ cytochromes $\rightarrow$ PS-I $\rightarrow$ NADP.