Question

The respiratory quotient during cellular respiration would depend on

• A. The nature of enzymes involved.
• B. The nature of the substrate.
• C. The amount of carbondioxide released.
• D. The amount of oxygen utilized.

Answer 1

Answer: (B)

The nature of the substrate.

The ratio of the volume of $C{O}_2$ evolved to the volume of $O_2$ consumed in respiration is called as the respiratory quotient (RQ) or respiratory ratio.

RQ volumeof CO evolved/volumeof O consumed. The respiratory quotient depends upon the type of respiratory substrate used during respiration. When carbohydrates are used as substrate and are completely oxidised, the RQ will be 1, because equal amounts of $C{O}_2$ and $O_2$ are evolved and consumed, respectively. When fats are used in respiration, the RQ is less than 1. When proteins are respiratory substrates the ratio would be about 0.9.