Which of the following is NOT classified as a monosaccharide?

Sucrose is not classified as a monosaccharide; rather, it is a disaccharide. Monosaccharides are simple sugars that consist of single sugar units, while disaccharides are composed of two monosaccharide units linked together.

Glucose, fructose, and galactose are all examples of monosaccharides. They each contain a single sugar molecule and cannot be further hydrolyzed into simpler sugars. In contrast, sucrose is made up of one glucose molecule and one fructose molecule bonded together. This structural difference is key to understanding the classification of these carbohydrates. Thus, recognizing the distinction between monosaccharides and disaccharides is crucial in carbohydrate chemistry and nutrition, which underpins the identification of sucrose as not being a monosaccharide.