15. The breakdown of lactose in the small intestine is mediated by the enzyme lactase, and the products are galactose and glucose. Galactose and glucose are which of the following?
Answer: D
Galactose and glucose are monosaccharides.
Galactose and glucose are both classified as monosaccharides, which are the simplest form of carbohydrates consisting of single sugar molecules.
A) Disaccharides
Disaccharides are carbohydrates composed of two monosaccharide units joined together. Since galactose and glucose are individual sugar molecules, they do not fit this classification.
B) Oligosaccharides
Oligosaccharides consist of a small number of monosaccharides (typically 3-10) linked together. Galactose and glucose, being single sugar units, do not qualify as oligosaccharides.
C) Polysaccharides
Polysaccharides are large carbohydrate molecules composed of long chains of monosaccharide units. As galactose and glucose are not composed of multiple sugar units, they cannot be categorized as polysaccharides.
D) Monosaccharides
Galactose and glucose are indeed monosaccharides, as they are both single sugar molecules that are produced from the breakdown of lactose by the enzyme lactase.
Conclusion
The definitive classification of galactose and glucose as monosaccharides is supported by their structure as single sugar units. All other options fail to accurately represent these sugars, as they pertain to more complex carbohydrate structures. Hence, D is the correct choice.