Which of the following best defines monosaccharides?

Monosaccharides are best defined as simple sugars, which includes examples such as glucose and fructose. They are the most basic form of carbohydrates and serve as fundamental building blocks for more complex carbohydrates. In the context of carbohydrate structure, monosaccharides are single-sugar molecules that cannot be hydrolyzed into smaller carbohydrate units.

Unlike complex carbohydrates, which are formed by the combination of multiple monosaccharides or other sugar units, monosaccharides exist independently as single entities. For instance, glucose is a primary source of energy for cells, and fructose is commonly found in fruits. These simple sugars can readily be absorbed and utilized by the body, making them vital for metabolic processes.

Understanding that monosaccharides are simple sugars helps clarify their role in nutrition and metabolism, distinguishing them from more complex forms of carbohydrates and other macromolecules such as fatty acids and glycerol.