What forms when two glucose molecules are combined?

When two glucose molecules combine, they undergo a dehydration synthesis reaction, resulting in the formation of maltose. This process involves the removal of a water molecule, and the two glucose units are held together by a glycosidic bond. Maltose is classified as a disaccharide, which is a type of carbohydrate composed of two monosaccharide units. In this case, maltose is specifically formed from two alpha-glucose molecules.

The other options represent different types of disaccharides made from varying combinations of monosaccharides. Sucrose, for instance, is formed from a glucose molecule and a fructose molecule, while lactose consists of a glucose molecule and a galactose molecule. Fructose, on the other hand, is a monosaccharide on its own and does not form from the combination of two glucose units. Understanding the specific combinations that yield these carbohydrates is key to grasping basic carbohydrate biochemistry and their classifications.