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🔬 Biology  ·  Respiration in Plants  ·  NEET

In the Krebs cycle, the step converting succinate to fumarate is notable because it is the only step where:

  • A ATP is generated directly through substrate-level phosphorylation in most observed cases under typical physiological conditions
  • B The enzyme involved sits in the inner mitochondrial membrane and feeds electrons to the transport chain
  • C Acetyl CoA condenses with oxaloacetate to begin the cycle according to standard texts in general clinical practice
  • D Carbon dioxide is released as a byproduct of the reaction in standard reference material under most conditions studied

Correct answer: B. The enzyme involved sits in the inner mitochondrial membrane and feeds electrons to the transport chain

Explanation: Succinate dehydrogenase, unlike other Krebs cycle enzymes, is embedded in the inner mitochondrial membrane and directly passes electrons to FAD, linking the cycle to the electron transport chain as Complex II.

Concept context

Glycolysis, the Krebs cycle, the electron transport chain, fermentation, and the respiratory quotient. The cellular energy-release counterpart to photosynthesis.

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