Question

Oxidation of which of the following substances in the body yields more amount of calories?
A) Glucose
B) Glycogen
C) Protein
D) Lipids

Answer 1

Hint: A calorie is an energy unit that is defined as the amount of heat required to raise the temperature of a volume of water by one degree. Two major definitions of calories are widely used for historical reasons.

Complete answer:
A biological process in which a negatively charged electron is transferred from one organic molecule to another or oxygen. Biological oxidation is a process that produces energy in living cells and is accompanied by a reduction reaction.

When one molecule loses an electron (oxidizes), another compound acquires an electron (reduces). The major source of cellular energy is oxidation-reduction (redox) processes. Oxidation and reduction processes happen at the same time, and one cannot happen without the other. The many breakdown products of the primary foodstuffs—carbohydrates, lipids, and proteins—are the main sources of reductants for animals. These compounds release energy by a sequence of hydrogen and electron transfers to molecular oxygen.

All aerobic organisms that utilize oxygen in their respiration mechanism undergo oxidation processes. Without molecular oxygen, the aerobic mode of cellular oxidation is impossible. The direct breakdown of nutrients for energy is referred to as oxidation. The largest energy level is found in fats or lipids, which contain 9 kcal/gm, whereas proteins and carbs have 4 kcal/gm.

Thus, the answer is option ‘D’ i.e, Lipids.

Note: Similar to acid-base reactions, oxidation and reduction occur concurrently and cannot occur independently of one another. Each half-reaction (oxidation and reduction) is referred to as a half-reaction because two half-reactions are usually combined to produce a full reaction. To balance the half-reaction in terms of electric charge, the acquired or lost electrons are usually explicitly mentioned when writing half-reactions. When the half-reactions are combined to form the net chemical equation, the electrons cancel out.