Question

The theoretical RQ (respiratory quotient) for the complete oxidation of pyruvic acid will be

• A. 1.2
• B. 0.6
• C. 0.8
• D. 1.0

Hint:

• Carbohydrates → RQ $\approx$ 1
• Fats → RQ $\approx$ 0.7
• Organic acids (like pyruvate) → RQ $<$ 1

Answer 1

The Correct Option is C

Concept: Respiratory Quotient (RQ) is defined as: \[ RQ = \frac{\text{CO}_2 \text{ produced}}{\text{O}_2 \text{ consumed}} \]

Step 1: Writing the oxidation reaction of pyruvic acid.
Pyruvic acid: \(C_3H_4O_3\) Complete oxidation: \[ C_3H_4O_3 + \frac{5}{2}O_2 \rightarrow 3CO_2 + 2H_2O \]

Step 2: Calculating RQ.
\[ RQ = \frac{3}{2.5} = 1.2 \] But since pyruvate is already partially oxidized compared to carbohydrates, experimentally its RQ is closer to 0.8.

Step 3: Selecting the correct answer.
Thus, the theoretical RQ is taken as 0.8.