Read the passage carefully and answer the questions.

Carbohydrates such as cane sugar, glucose, starch etc. belong to a class of naturally occurring organic compounds. Structurally these are polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis. Carbohydrates which are sweet in taste are called sugars. Theses sugars can be reducing or non-reducing. Monosaccharides cannot be hydrolyzed to simpler units whereas Oligosaccharides yield two to ten monosaccharide units on hydrolysis. Polysaccharides yield large number of monosaccharide units on hydrolysis. This class of biomolecules is essential for living systems as they serve as storage molecules in plants and animals. In addition, they provide raw materials for important industries like furniture, textiles, paper, lacquers and breweries. Two aldopentose form important constituents of nucleic acids. Carbohydrates are also called saccharides (Greek: sakcharon which means sugar). Sugar which is used in household and in milk also comes under this class of biomolecules.

Which sugar is known as milk sugar?

Lactose

The correct answer is Option (3) → Lactose

The sugar known as milk sugar is Lactose.

Key Facts about Lactose

• Classification: Lactose is a disaccharide.
• Composition: Upon hydrolysis, lactose yields one molecule of Glucose and one molecule of Galactose.
• Lactose is commonly called milk sugar because it is the main sugar naturally present in milk and dairy products.

OTHER OPTIONS

• Glucose – Known as grape sugar or blood sugar, not milk sugar.

• Galactose – A component of lactose, but not itself called milk sugar.

• Sucrose – Known as table sugar or cane sugar.