Which one of the following statements is not true?
Biomolecules · Class 12 · JEE Main Previous Year Question
Which one of the following statements is not true?
- a✓
Lactose contains -glycosidic linkage between of galactose and of glucose.
- b
Lactose is a reducing sugar and it gives test.
- c
On acid hydrolysis, lactose gives one molecule of and one molecule of .
- d
Lactose is a disaccharide and it contains hydroxyl groups.
Lactose contains -glycosidic linkage between of galactose and of glucose.
Step 1: Analyzing Disaccharide Linkages — Lactose is made of and . The glycosidic bond is formed between of galactose and of glucose.
Step 2: Stereochemical Correction — Importantly, this bond is the -anomeric form. Statement (a) claims it is an -linkage, which is incorrect.
Step 3: Verifying Other Facts — Lactose is indeed a reducing sugar, yields glucose and galactose upon hydrolysis, and possesses eight hydroxyl () groups. Thus, only (a) is false.
Key Point: The linkage is a fundamental structural feature of milk sugar.
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