Question

The physiological value of carbohydrates is

• A. 4.0 kcal/g
• B. 5.65 kcal/g
• C. 4.1 kcal/g
• D. 9.0 kcal/g

Answer 1

The correct option is A 4.0 kcal/g

$\begin{array}{ccc}\text{Respiratory}& \text{Gross Calorific}& \text{Physiological}\\ \text{Substrate}& \text{Value (kcal/g)}& \text{Value (kcal/g)}\\ \text{Carbohydrate}& 4.1& 4.0\\ \text{Lipid}& 9.45& 9.0\\ \text{Protein}& 5.65& 4.0\end{array}$

The amount of energy liberated from complete oxidation of 1g the respiratory substrate in a bomb calorimeter (a closed metal chamber filled with oxygen) is its gross calorific value.

The actual amount of energy released by oxidation of 1g of the respiratory substrate in the body is the physiological value. The physiological value of carbohydrates is 4 kcal/g.