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MDCAT Biology QUESTION #11250
Question 1
The chemiosmotic theory explains ATP synthesis by proposing that:
  • ATP is produced directly by substrate-level phosphorylation
  • A proton gradient across the inner mitochondrial membrane drives ATP synthase✔️
  • Electrons flow directly from NADH to ATP
  • Oxygen directly phosphorylates ADP
Correct Answer Explanation
The chemiosmotic theory (Peter Mitchell) proposes that the electron transport chain pumps protons across the inner mitochondrial membrane, creating an electrochemical gradient. Protons flow back through ATP synthase, driving the phosphorylation of ADP to ATP.