The correct answer is option 2. A, C and D only.
Let us go through each option in detail:
(A) Maltose: It is a reducing sugar. Maltose is a reducing sugar. It is composed of two glucose molecules linked by an α(1→4) glycosidic bond. The linkage involves the anomeric carbon of one glucose and the hydroxyl group of another. This allows one of the glucose units to have a free reducing aldehyde group, making maltose a reducing sugar.
(B) Sucrose: It is a non-reducing sugar. Sucrose is a non-reducing sugar. It is composed of glucose and fructose units linked by a glycosidic bond between the anomeric carbon of glucose and the hydroxyl group of fructose. In sucrose, both glucose and fructose lose their free-reducing groups due to the formation of this glycosidic linkage.
(C) Lactose: It is a reducing sugar. Lactose is a reducing sugar. It is composed of galactose and glucose units linked by a β(1→4) glycosidic bond. The linkage involves the anomeric carbon of one sugar and the hydroxyl group of another, leaving one of the glucose units with a free-reducing aldehyde group.
(D) Fructose: It is a reducing sugar. Fructose is a reducing sugar. Although fructose itself is a ketose (contains a keto group), it can convert to an aldehyde in certain conditions, allowing it to act as a reducing agent.
(E) Cellulose: It is a non-reducing sugar. Cellulose is a non-reducing polysaccharide. It is composed of glucose units linked by β(1→4) glycosidic bonds. The linkage results in the loss of free-reducing groups in the glucose units.
So, the correct answer is option 2: A, C, and D only. Maltose, lactose, and fructose are reducing sugars due to the presence of free-reducing groups, while sucrose and cellulose are non-reducing. |
