Question

During proton pump (chemiosmosis) for synthesis of NADPH$_2$ from NADP ______ are required.

• A. only protons
• B. only electrons
• C. neither protons nor electrons
• D. protons along with electrons

Hint:

Reduction reactions always involve gain of electrons, often accompanied by protons.

Answer 1

The Correct Option is D

Step 1: Understanding NADPH$_2$ formation.
During the light reaction of photosynthesis, NADP$^+$ is reduced to NADPH$_2$. This reduction requires the transfer of electrons as well as protons (H$^+$ ions).
Step 2: Analyzing the options.
(A) only protons: Incorrect. Protons alone cannot reduce NADP$^+$.
(B) only electrons: Incorrect. Both electrons and protons are required.
(C) neither protons nor electrons: Incorrect. Reduction cannot occur without them.
(D) protons along with electrons: Correct. NADP$^+$ accepts both electrons and protons to form NADPH$_2$.
Step 3: Conclusion.
The correct answer is (D) protons along with electrons.