RQ Value

• The Respiratory Quotient (RQ) is a ratio of gas exchange, calculated by comparing the oxygen uptake with the carbon dioxide involved. The RQ value can be used to estimate what substrate is being used and what type of respiration is occurring 
• RQ = volume (or molecules) of carbon dioxide released

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  volume (or molecules) of oxygen consumed
• If the RQ value is equal to or less than 1, but not less than 0.9, then carbohydrate is the respiratory substance
• If the RQ value is equal to or less than 0.9, but not less than 0.7, then fatty acid is the respiratory substance
• If the RQ value is equal to or less than 0.7, then protein is the respiratory substance
• The RQ value of alcoholic fermentation is infinity
• An RQ value of more than 1 suggests that some anaerobic respiration is taking place, when anaerobic respiration occurs normally both aerobic and anaerobic respiration are occurring
• The aerobic component will produce an RQ value of 0.7-1 but anaerobic respiration will involve the production of carbon dioxide in plants and fungi without the input of oxygen. Therefore, the higher the RQ value, the higher the amount of anaerobic respiration 

  This only applies to plants and fungi as mammals do not release carbon dioxide as a waste product of anaerobic respiration