Question

Calorific value of carbohydrates, protein and fats are
A. 4.1kcal/g , 5.65kcal/g , 9.45kcal/g
B. 5.65kcal/g , 10kcal/g , 2.3kcal/g
C. 3.1kcal/g , 9 kcal/g , 6kcal/g
D. None of the above

Answer 1

Hint: Calorific value is the amount of energy which is present in a food or fuel and it’s determined by measuring the heat produced by complete combustion of it with oxygen of specific quantity. It is measured in kcal/g. Or it is defined as the energy value of food and fuel indicating how much energy gained by metabolism of the human body.

Complete step by step answer:
Carbohydrates: -They are naturally occurring sugar, fibres and starch in food. When metabolized glucose converts into pyruvate during glycolysis and even to lactate when there is absence of oxygen. For example: vegetables, pasta, rice, grain and each gram of carbohydrates contain 4kacl/g.
Protein: - Protein is macromolecules and is a polymer of amino acids which are the building blocks of life. Proteins are the necessary macromolecules whose deficiency in the body can lead to some disorders. Sources of proteins are:- egg, meat, poultry products. The calorific value of proteins is the same as carbohydrates.
Fats:- Fats are the slowest form of energy and lately digest. Some foods like sausages, potato contain higher calories and lower vitamins and minerals so that as compared to above two fats have high calorific value.
To calculate the calorific value any macromolecule:
The formula used will be $\dfrac{{{\text{heat}}}}{{{\text{kilogram}}}}$
Heat calculated in the above formula will be measured in kilojoules kilogram which is equal to total combustion in kg
Thus the correct option is A.

Note: Carbohydrates, proteins and fats are very essential for us. Carbohydrates and protein can easily be metabolized by glucose or Krebs cycle but due to slowest form of energy fats not easily metabolised. The source of these macromolecules in humans is our food diet.