Which nutrient category is used by the body to build and maintain its cells and tissues?

• A. Proteins
• B. Carbohydrates
• C. Nucleic Acids
• D. Amino Acids

Answer: (A)

Proteins are the main building blocks of the body's cells and tissues. They provide the structural framework that makes up tissues like skin, muscles, bones, and connective tissue, and they also form enzymes and other proteins that keep tissues functioning and able to repair themselves after injury. The body uses amino acids as the building blocks to synthesize these proteins, so while amino acids are essential, the category that directly builds and maintains tissue structure is proteins themselves. Carbohydrates mainly supply energy and can contribute to some matrix components, but they’re not the primary structural material of tissues. Nucleic acids store genetic information and direct protein production, rather than composing the tissues themselves.