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BioTechnology QUESTION #10557
Question 1
In aerobic respiration, the maximum ATP yield from one mole of glucose via the P/O ratio is closest to:
  • $P/O = 1$, giving ~19 ATP
  • $P/O = 2$, giving ~38 ATP
  • $P/O \approx 2.5$, giving ~30–32 ATP✔️
  • $P/O = 3$, giving ~36 ATP
Correct Answer Explanation
Modern biochemistry revises the classical '38 ATP' figure. With realistic P/O ratios of ~2.5 for NADH and ~1.5 for FADH₂, complete aerobic oxidation of glucose yields approximately 30–32 ATP. The equation is: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \Delta G$. Substrate-level phosphorylation contributes only 4 ATP; the rest comes from oxidative phosphorylation.