Question

Which of the following biomolecule reacts with ninhydrin in development of latent prints ?

• A. Lipids
• B. Carbohydrates
• C. Amino acids
• D. Nucleic acids

Hint:

Ninhydrin + Amino acids → Purple color (Ruhemann’s purple) → Visible fingerprints.

Answer 1

The Correct Option is C

Concept: Latent fingerprints are developed using chemical reagents that react with specific components of sweat residue left on surfaces. One of the most widely used reagents is ninhydrin.

Step 1: Understanding latent fingerprints.
Latent prints are invisible impressions left by the friction ridges of fingers. These prints contain sweat, which is composed of water, salts, amino acids, lipids, and other organic substances.

Step 2: Role of ninhydrin.
Ninhydrin is a chemical reagent that specifically reacts with amino acids present in the sweat residue of fingerprints.

Step 3: Chemical reaction.
When ninhydrin reacts with amino acids, it produces a deep purple-colored compound known as Ruhemann’s purple, making the fingerprint visible.

Step 4: Evaluating options.

• Lipids – Not reactive with ninhydrin.
• Carbohydrates – Do not produce the characteristic color reaction.
• Amino acids – Correct, react strongly with ninhydrin.
• Nucleic acids – Not involved in this reaction. Final Conclusion:
Thus, the correct answer is amino acids.