The Question is from neet-botany respiration-in-plants , and it was created by the author D VINOD

Question

Which specific component of the electron transport chain is directly responsible for the reduction of oxygen to water during aerobic respiration?

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
 **Primary Concept**: Electron Transport Chain (ETC) and Oxidative Phosphorylation
 **Related Topics**: Aerobic respiration, cellular respiration, redox reactions, mitochondrial function
 **Prerequisites**: Understanding of electron carriers, proton gradient, and ATP synthesis.
## SOLUTION PATHWAY
**Given Information**:
  The question asks about the specific component of the electron transport chain responsible for the reduction of oxygen ($O_2$) to water ($H_2O$).
  [Important conditions]: This process occurs during aerobic respiration in the mitochondria.
**Method & Steps**:
 1. Identify the final electron acceptor in the electron transport chain.
  Reasoning: The electron transport chain involves a series of redox reactions where electrons are passed from one carrier to another, ultimately transferring energy to create a proton gradient. The final electron acceptor is the molecule that receives these electrons at the end of the chain.
  Formula/Rule:  $O_2 + 4e^- + 4H^+ ightarrow 2H_2O$
 2. Determine which complex catalyzes the reduction of oxygen.
  Working:  Cytochrome c oxidase (Complex IV) is the terminal enzyme in the ETC. It receives electrons from cytochrome c and uses them to reduce molecular oxygen ($O_2$) to water ($H_2O$). This reaction is coupled with the pumping of protons across the inner mitochondrial membrane, contributing to the proton gradient essential for ATP synthesis.
  Key Point:  Other complexes in the ETC (NADH dehydrogenase, succinate dehydrogenase, cytochrome bc1 complex) are involved in electron transport, but they don't directly reduce oxygen to water.
 3. Conclude which option is correct.
  Result: Cytochrome c oxidase is directly responsible for the reduction of oxygen to water.
  Verification: The balanced chemical equation for the reduction of oxygen by cytochrome c oxidase confirms this.
 ## OPTION ANALYSIS
[A] :x: NADH dehydrogenase:  Part of Complex I, involved in early electron transport, but doesn't directly reduce oxygen.
[B] :x: Succinate dehydrogenase: Part of Complex II,  involved in early electron transport, but doesn't directly reduce oxygen.
[C] :x: Cytochrome bc1 complex:  Complex III, involved in electron transport, but doesn't directly reduce oxygen.
[D] ✓: Cytochrome c oxidase: The terminal enzyme of the ETC, directly responsible for reducing oxygen to water.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the roles of different complexes in the ETC: Understanding the specific function of each complex is crucial.
   [How to avoid]:  Create a flow chart or diagram of the ETC showing the electron flow and the function of each complex.
  2.Forgetting that water is a product of oxygen reduction:  The final step of aerobic respiration involves the reduction of oxygen to water.
   [How to avoid]: Memorize the balanced chemical equation for this reaction.
 **Quick Tips**:
  1.Remember the order of the complexes in the ETC (I, II, III, IV) and their functions.
  2.Associate cytochrome c oxidase with the final step of oxygen reduction to water.

D VINOD · Answer

NADH dehydrogenase

D VINOD · Answer

Succinate dehydrogenase

D VINOD · Answer

Cytochrome bc1 complex

D VINOD · Answer

The correct Option is "Cytochrome c oxidase"

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