Question

Final electron acceptor in oxidative phosphorylation is

• A. Oxygen
• B. NAD$^{+}$
• C. FAD
• D. ATP

Hint:

Remember: \[ \boxed{\text{Final Electron Acceptor in Aerobic Respiration}=O_2} \] Without oxygen, the Electron Transport Chain stops and ATP production decreases drastically.

Answer 1

The Correct Option is A

Concept: Oxidative phosphorylation is the final stage of aerobic respiration and occurs on the inner mitochondrial membrane. During this process, electrons released from NADH and FADH$_2$ pass through a series of electron carriers known as the Electron Transport Chain (ETC). The energy released is used to produce ATP, while oxygen acts as the terminal (final) electron acceptor.

Step 1: Understand the Electron Transport Chain.
Electrons produced during glycolysis and the Krebs cycle are carried by NADH and FADH$_2$ to the Electron Transport Chain. \[ \boxed{\text{NADH/FADH}_2 \rightarrow \text{ETC} \rightarrow O_2} \] As electrons move through the ETC, energy is released for ATP synthesis.

Step 2: Role of oxygen.
At the end of the Electron Transport Chain, oxygen accepts electrons and combines with hydrogen ions. \[ O_2+4e^-+4H^+ \longrightarrow 2H_2O \] Thus, oxygen is reduced to water.

Step 3: Eliminate incorrect options.

• NAD$^{+}$ accepts electrons earlier in respiration but is not the final electron acceptor.
• FAD also acts as an electron carrier.
• ATP is the product of oxidative phosphorylation.
• Oxygen is the terminal electron acceptor. Final Answer: \[ \boxed{Option (A) is correct \]