Monosaccharides that are the main energy source for cells belong to which macromolecule group?

• A. Carbohydrates
• B. Lipids
• C. Proteins
• D. Nucleic acids

Answer: (A)

Monosaccharides are simple sugars that form the carbohydrate family, the main source of cellular energy. When cells metabolize glucose through glycolysis and related pathways, they generate ATP, the energy currency that powers most cellular processes. Carbohydrates also include larger energy-storage molecules built from these sugar units, like glycogen and starch, which store energy for later use. Other macromolecules have different primary roles: lipids mainly provide long-term energy storage and form membranes, proteins perform structural and catalytic functions, and nucleic acids store and transmit genetic information. Because monosaccharides are the basic units of carbohydrates and carbohydrates are the primary energy-providing macromolecules, this group best fits the description.