Disaccharides are

• A. three monosaccharides joined together
• B. two monosaccharides joined together
• C. one monosaccharide with a phosphate group
• D. polysaccharides

Answer: (B)

Disaccharides are composed of two monosaccharide units linked by a glycosidic bond formed through a dehydration reaction. The name itself reflects two sugar units, which is exactly why two monosaccharides joined together is the correct description. Examples like maltose (two glucose units), lactose (glucose and galactose), and sucrose (glucose and fructose) illustrate this two-unit structure. In contrast, a molecule with three monosaccharides would be a trisaccharide, a single monosaccharide with a phosphate group isn’t a disaccharide, and polysaccharides are long chains made of many sugars. Disaccharides are also typically soluble and sweet.