respiratory quotient

(RQ) The ratio of the volume of carbon dioxide evolved during respiration to the volume of oxygen absorbed, i.e. RQ = volume C0₂/ volume O₂. The complete respiratory breakdown of sugars by *aerobes often gives an RQ value of one, but it rises very considerably under anaerobiosis. When fats or proteins are used in respiration, the RQ value is less than one as less carbon dioxide is produced.