A, B and C are three biomolecules. The results of the tests performed on them are given below: | | Molisch's Test |…
Biomolecules · Class 12 · JEE Main Previous Year Question
A, B and C are three biomolecules. The results of the tests performed on them are given below:
| | Molisch's Test | Barfoed Test | Biuret Test | | :--- | :--- | :--- | :--- | | (A) | Positive | Negative | Negative | | (B) | Positive | Positive | Negative | | (C) | Negative | Negative | Positive |
A, B and C are respectively:
- a
A = Lactose, B = Glucose, C = Alanine
- b✓
A = Lactose, B = Glucose, C = Albumin
- c
A = Glucose, B = Fructose, C = Albumin
- d
A = Lactose, B = Fructose, C = Alanine
A = Lactose, B = Glucose, C = Albumin
Step 1: Molisch's Test — Positive for A and B means both are carbohydrates. Negative for C means it matches a non-carbohydrate like a protein.
Step 2: Barfoed's Test — Positive for B indicates it is a monosaccharide. Negative for A suggests it is a disaccharide or polysaccharide.
Step 3: Biuret Test — Positive for C confirms it is a protein with peptide bonds. This sequence matches A = Lactose (Disaccharide), B = Glucose (Monosaccharide), C = Albumin (Protein).
Key Point: Comparison between Barfoed's and Molisch's allows differentiation between carbohydrate classes.
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