What type of reaction links monosaccharides to form disaccharides?

• A. Condensation reaction
• B. Hydrolysis
• C. Oxidation
• D. Reduction

Answer: (A)

Forming a disaccharide from two monosaccharides happens through dehydration synthesis, a condensation reaction. In this process, the hydroxyl group of one sugar and a hydrogen from the other are removed as water, allowing the two units to join with a glycosidic bond. This bond formation releases a water molecule and links the sugars into a larger carbohydrate, as seen in maltose, lactose, and sucrose. Hydrolysis would do the opposite—use water to break that bond and yield two monosaccharides. Oxidation or reduction involve electron transfer and do not specifically create the sugar–sugar linkage.