Different substrates get oxidized during respiration. How does Respiratory Quotient (RQ) indicate which type of substrate, i.e., carbohydrate, fat or protein is getting oxidized?
R. Q. = 
What do A and B stand for?
What type of substrates have R.Q. of 1, < 1 or > 1?
Respiratory Quotient (RQ) indicate which type of substrate, i.e., carbohydrate, fat or protein is getting oxidized by measuring the volume of carbon dioxide, i.e., CO2 released or evolved by the volume of oxygen O2 consumed. It is a unitless quantity. The ratio helps in determining the type of substrate.
A stands for volume of carbon dioxide, i.e., CO2 released or evolved.
B stands for the volume of oxygen O2 consumed.
RQ less than 1 = fat or protein.
RQ equal to 1 = carbohydrate like glucose.
RQ higher than 1 = substrate can be organic acid like malic acid.