NEET BIOLOGY

CELL STRUCTURES AND FUNCTION

BIO MOLECULES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Biruet’s Solution tests for
A
Carbohydrates
B
Proteins
C
Nucleic Acids
D
Lipids
Explanation: 

Detailed explanation-1: -A small amount of this aqueous solution must be treated with 1% sodium hydroxide or potassium hydroxide. To this mixture, a few drops of CuSO4 (aq) must be added. If the solution turns purple upon the addition of copper(II) sulphate, the presence of protein in the analyte is confirmed.

Detailed explanation-2: -(a) Biuret Test: Add 2ml of sodium hydroxide and 5 to 6 drops of copper sulfate solution to it. Shake the test tube gently to mix the ingredients thoroughly and allow the mixture to stand for 4 – 5 minutes. If there is the appearance of bluish-violet color, it indicates the presence of protein.

Detailed explanation-3: -We used Biuret’s reagent to detect the presence of proteins in solution. The reagent is pale blue when pure, but when mixed with proteins, the resulting reaction produces a pale purple color.

Detailed explanation-4: -Since all proteins and peptides possessing at least two peptide linkage ie. tripeptide gives positive biuret test. The principle of biuret test is conveniently used to detect the presence of proteins in biological fluids.

There is 1 question to complete.