Biology – Energy | e-Consult

The respiratory quotient (RQ) is significant because it provides information about the type of fuel being used for respiration and, consequently, the amount of energy being released. The RQ is the ratio of CO₂ produced to O₂ consumed.

A RQ of 1 indicates that glucose is being fully oxidized (aerobic respiration), producing CO₂ and water. A RQ of 0.7 indicates that fat is being respired (aerobic respiration), which is less fully oxidized than glucose and produces less CO₂. A RQ of 0.8 indicates that protein is being respired (aerobic respiration), which is the least fully oxidized and produces the least CO₂.

The RQ relates to the level of oxidation of the fuel. Higher RQ values (closer to 1) indicate a more fully oxidized fuel source (like glucose), while lower RQ values (closer to 0) indicate a less fully oxidized fuel source (like protein). This difference in oxidation state directly affects the amount of CO₂ produced.