The ratio of carbon dioxide produced to oxygen consumed, indicating which fuel is being used.
Measured by respirometers. Values: carbohydrate 1.0, protein 0.8, fat 0.7. Mixed diets give about 0.8 to 0.85. It indicates metabolic state, for example in starvation or ketogenic diets.
RQ values reflect substrate. High-carb diets raise RQ; fasting lowers it. RQ above 1 can mean lipogenesis.
Example: RQ is measured using a respirometer with soda lime to absorb CO2.
The ratio of carbon dioxide produced to oxygen consumed, indicating which fuel is being used.
Respiratory Quotient is one of the 53 topics in Metabolism & Bioenergetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Respiratory Equation, Ketone Body Metabolism, Alcoholic Fermentation.
Germinating seeds with fats have a lower RQ than those with starch.
Work through the Beginner topics in Metabolism & Bioenergetics first, such as Metabolism, Anabolism and Catabolism, ATP, then return to Respiratory Quotient. Intermediate topics assume the Beginner vocabulary.
The closest topics to Respiratory Quotient are Respiratory Equation, Ketone Body Metabolism, Alcoholic Fermentation, Hormonal Control of Metabolism. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Respiratory Quotient. To practise the whole of Metabolism & Bioenergetics, use the Metabolism & Bioenergetics quiz.
Respiratory Quotient: The ratio of carbon dioxide produced to oxygen consumed, indicating which fuel is being used. Respiratory Equation: Glucose plus oxygen yields carbon dioxide, water and energy released as ATP and heat. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Respiratory Equation and explain the difference aloud. Finally, take the Metabolism & Bioenergetics quiz and come back to this page for any question you miss.
Glucose plus oxygen yields carbon dioxide, water and energy released as ATP and heat.
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