Question

The number of ATP molecules generated in aerobic respiration after oxidation of two molecules of pyruvic acid is.

• A. 6
• B. 12
• C. 24
• D. 30

Hint:

Memory trick: 1 Pyruvate $\rightarrow$ 15 ATP
2 Pyruvate $\rightarrow$ 30 ATP

Answer 1

The Correct Option is D

Concept: In aerobic respiration, pyruvic acid undergoes complete oxidation in the mitochondria through link reaction and Krebs cycle, followed by oxidative phosphorylation.
• Each pyruvate produces:
• 4 NADH (1 from link reaction + 3 from Krebs cycle)
• 1 FADH$_2$
• 1 ATP (substrate level)

Step 1: Calculate yield from one pyruvate.
• NADH: $4 \times 3 = 12$ ATP
• FADH$_2$: $1 \times 2 = 2$ ATP
• Direct ATP: $1$ Total = $12 + 2 + 1 = 15$ ATP

Step 2: For two pyruvate molecules.
$15 \times 2 = 30$ ATP

Step 3: Conclusion.
Thus, oxidation of two pyruvic acid molecules yields 30 ATP. Final Answer:Option (D)