Answer: Biuret test.
- A Biuret test
- B Fehling's test
- C Iodine test
- D Tollens' test
Correct answer: A. Biuret test
Explanation: The Biuret test detects peptide bonds; proteins give a violet/purple colour with Cu<sup>2+</sup> in alkaline solution.
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.