Multiple choice

If the volume of CO2 liberated during respiration is more than the volume of O2 used, the respiratory substrate will be a/an

  1. carbohydrate

  2. fat

  3. protein

  4. organic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The respiratory quotient (RQ = CO2 produced/O2 consumed) indicates substrate type. Carbohydrates have RQ = 1, fats have RQ ≈ 0.7, proteins have RQ ≈ 0.8. Organic acids have RQ > 1 because they are already partially oxidized and release more CO2 than oxygen consumed during their complete metabolism.

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