Question

Lactose is a disaccharide formed between C-1 of ....... and C-4 of ..........

• A. Galactose, Glucose
• B. Fructose, Glucose
• C. Glucose, Fructose
• D. Glucose, Galactose
• E.

Hint:

Lactose = Galactose + Glucose, joined by a β-1,4 glycosidic bond.

Answer 1

The Correct Option is A

Step 1: Understanding Lactose.
Lactose is a disaccharide composed of two monosaccharides, galactose and glucose.
It is formed through a glycosidic bond between C-1 of galactose and C-4 of glucose.
Step 2: Analyzing the options.
- (1) Galactose, Glucose: Correct. Lactose is made of galactose and glucose.
- (2) Fructose, Glucose: Incorrect. Lactose does not contain fructose.
- (3) Glucose, Fructose: Incorrect. Lactose is not composed of glucose and fructose.
- (4) Glucose, Galactose: Incorrect. The linkage is C-1 of galactose and C-4 of glucose, so the order here is incorrect.
Step 3: Conclusion.
Therefore, lactose is formed between C-1 of galactose and C-4 of glucose.