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NEET CHEMISTRYBiomoleculesMedium

Question

Which one of the following statements is not true regarding (+) lactose?

A

(+) lactose is a β\beta-glycoside formed by the union of a molecule of D(+) glucose and a molecule of D(+) galactose

B

(+) lactose is a reducing sugar and does not exhibit mutarotation

C

(+) lactose, C12H22O11\text{C}_{12}\text{H}_{22}\text{O}_{11} contains 8 -OH groups

D

On hydrolysis (+) lactose gives equal amounts of D(+) glucose and D(+) galactose

Step-by-Step Solution

Lactose is composed of β\beta-D-galactose and β\beta-D-glucose linked by a β\beta-1,4-glycosidic bond. Because the anomeric carbon (C1) of the glucose unit is free (not involved in the glycosidic bond), lactose is a reducing sugar. Molecules with a free anomeric carbon can undergo ring opening and closing in an aqueous solution, allowing them to exist in equilibrium between α\alpha and β\beta anomers. This process is known as mutarotation. Therefore, the statement that lactose does not exhibit mutarotation is incorrect.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Biomolecules. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYBiomoleculesfollowingstatementsregardinglactose

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