This question asks to identify which macronutrient provides the highest energy per gram. We need to recall the typical energy yield (in kilocalories per gram, kcal/g) for each of the major macronutrients: proteins, carbohydrates, and fats, and also consider dietary fibre.
Correct Option: D) Fats (9 kcal/g)
The question asks about the primary and most readily available source of energy for the human body. This requires knowledge of basic human physiology and nutrition, specifically how macronutrients are utilized for energy.
Correct Option: B) Carbohydrates
This question tests knowledge about the energy content of macronutrients. The energy values of carbohydrates, proteins, and fats are standard nutritional facts.
Correct Option: A) The energy value of carbohydrates is \(4 \text{ kcal/g}\) and that of proteins is also \(4 \text{ kcal/g}\). This is a widely accepted nutritional fact.
The question asks to identify a monosaccharide from the given options. To answer this, we need to understand the classification of carbohydrates, specifically what defines a monosaccharide, disaccharide, and polysaccharide.
C) Glucose is a monosaccharide. It is a simple sugar and the primary source of energy for living organisms.
The question asks about the primary storage sites for glycogen, which is the storage form of carbohydrates in animals. We need to identify the organs where glycogen is predominantly stored and utilized.
Correct Option: B) Liver and muscles
Glycogen is predominantly stored in the liver and skeletal muscles. The liver stores about 100g of glycogen (approximately 6% of its weight), which is used to maintain blood glucose levels. Muscles store about 400g of glycogen (approximately 1% of their weight), which is used as an energy source for muscle contraction.
The question asks why humans cannot digest cellulose. This is a common biological concept related to human digestive physiology and enzyme specificity. We need to identify the specific reason related to the breakdown of cellulose.
D) Humans lack the enzyme cellulase to break \(\beta\)-1,4-glycosidic bonds — This is the correct reason. The absence of the specific enzyme (cellulase) required to hydrolyze the unique \(\beta\)-1,4-glycosidic linkages in cellulose prevents humans from digesting it.