Question:hard

The electron transport system present in the mitochondrial membrane, complex-II and complex-IV are respectively:

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Complex II = Succinate; Complex IV = Cytochrome oxidase.
Updated On: Jun 6, 2026
  • NADH dehydrogenase, Cytochrome 'c' reductase
  • NADH dehydrogenase, Cytochrome 'c' oxidase
  • Succinic dehydrogenase, Cytochrome 'c' oxidase
  • Succinic dehydrogenase, Cytochrome 'c' reductase
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Read carefully.
We need the names of Complex II and Complex IV of the mitochondrial electron transport chain, in that order.

Step 2: Quick map of the chain.
The inner mitochondrial membrane carries four complexes. Complex I is NADH dehydrogenase, Complex II is succinic dehydrogenase, Complex III is cytochrome c reductase, and Complex IV is cytochrome c oxidase.

Step 3: Find Complex II.
Complex II is succinic dehydrogenase. It is the same enzyme that converts succinate to fumarate in the Krebs cycle, so it links respiration directly to the chain.

Step 4: Find Complex IV.
Complex IV is cytochrome c oxidase. It hands the electrons over to oxygen, the final acceptor, forming water.

Step 5: Match to options.
So the pair is succinic dehydrogenase and cytochrome c oxidase. Options naming NADH dehydrogenase belong to Complex I, and cytochrome c reductase belongs to Complex III, so they are wrong.

Step 6: Conclusion.
Therefore the correct answer is "Succinic dehydrogenase, Cytochrome 'c' oxidase". \[ \boxed{\text{Succinic dehydrogenase, Cyt c oxidase}} \]
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