What is the outcome when glucose is combined with galactose?

When glucose is combined with galactose, the resulting compound is lactose. Lactose is a disaccharide sugar that is primarily found in milk and dairy products. It is formed through a condensation reaction in which one molecule of glucose and one molecule of galactose are linked together by a glycosidic bond.

Understanding the formation of lactose involves recognizing that the combination of different monosaccharides can yield various disaccharides. Glucose and galactose, specifically, are the building blocks that make up lactose, which is crucial for providing energy, particularly in young mammals. Lactase is the enzyme responsible for breaking down lactose into its constituent monosaccharides for digestion.

The other options listed all represent different combinations of sugars: maltose is formed from two glucose molecules, sucrose from glucose and fructose, and ribose is a monosaccharide that is not formed from glucose and galactose. Thus, the knowledge of carbohydrate chemistry confirms that the correct outcome of glucose combined with galactose is indeed lactose.