Which category of macromolecules serves primarily as a source of stored energy?

Carbohydrates are the primary macromolecules that serve as a source of stored energy in living organisms. They are composed of sugar molecules and can be found in various forms, including monosaccharides (like glucose), disaccharides (like sucrose), and polysaccharides (like starch and glycogen).

When consumed, carbohydrates can be broken down into glucose, which is then utilized by the body as a readily available energy source. Additionally, excess glucose can be stored in the liver and muscles as glycogen, providing a reserve of energy that can be mobilized when needed.

In contrast, nucleic acids primarily function in the storage and transmission of genetic information, making them crucial for cellular functions and heredity, but not as energy sources. Proteins play important roles in structure, function, and regulation within cells and can serve as an energy source if necessary, but they are not the primary macromolecule for energy storage. Minerals are inorganic elements that are essential for various physiological functions and do not qualify as macromolecules, as they do not provide energy themselves.

Thus, carbohydrates are the most efficient and favored source of stored energy in biological systems.