Question

When the respiratory substances are more than one then which respiratory substrates are not used?

• A. Pure protein
• B. Lipid
• C. Carbohydrate
• D. Both (a) and (b)

Answer 1

The correct option is D Both (a) and (b)

A respiratory substrate is a molecule from which energy can be liberated to produce ATP in a living cell. Glucose is not the only respiratory substrate. All carbohydrates, lipids and proteins can also be used as respiratory substrates. Respiratory Quotient (RQ) can be measured by the ratio of the volume of carbon dioxide evolved to that of oxygen consumed by an organism, tissue, or cell in a given time i.e, RQ = VCO${}_2$/VO${}_2$.


Here, from the above table infers that lipid and protein will have a lower RQ value than 1, since more oxygen will be needed to oxidize the fats and lipids then to oxidize the carbohydrates.
So, the correct answer is option D.