Define RQ. Write a short note on RQ.

The ratio of the volume of CO₂ evolved to the volume of O₂ consumed in respiration is called the respiratory quotient (RQ).
$\mathrm{RQ}=\frac{\text{ Volume of }{\mathrm{CO}}_2\text{ evolved }}{\text{ Volume of }{\mathrm{O}}_2\text{ consumed }}$
* When carbohydrates are used as substrate the RQ is 1, because equal amount of CO₂ and O₂
are evolved and consumed.
$\mathrm{RQ}=\frac{6{\mathrm{CO}}_2}{6{\mathrm{O}}_2}=1.0$
* When fats are used in respiration the RQ is less than 1
$\mathrm{RQ}=\frac{102{\mathrm{CO}}_2}{145{\mathrm{O}}_2}=0.7$
* When protein are respiratory substrates the ratio would be about 0.8 to 0.9.