(A) P-4, Q-1, R-2, S-3

(B) P-1, Q-4, R-3, S-2

(C) P-2, Q-3, R-4, S-1

(D) P-3, Q-4, R-1, S-2

Introduction

Matching biophysical techniques with their applications is a frequently tested concept in exams such as CSIR-NET, GATE, IIT-JAM, and MSc entrance tests.
This question evaluates your understanding of protein structure analysis, biochemical separation methods, and sample processing techniques.
Let us solve the question “Match the items in Group I with Group II” using clear concepts and eliminate incorrect options logically.

Correct Conceptual Matching

1. Circular Dichroism → Secondary Structure Determination

• Circular dichroism (CD) measures differential absorption of left- and right-circularly polarized light.

• It is widely used to analyze α-helix, β-sheet, and random coil content of proteins.

• Correct match: P-3

2. X-ray Crystallography → Tertiary Structure Determination

• X-ray crystallography provides atomic-level 3D structures of biomolecules.

• It reveals precise folding and spatial arrangement of amino acids.

• Correct match: Q-4

3. Freeze-Drying → Concentration

• Freeze-drying (lyophilization) removes water under low pressure.

• It is used to concentrate and preserve biological samples without denaturation.

• Correct match: R-1

4. Ultracentrifugation → Sedimentation Coefficient

• Ultracentrifugation separates molecules based on size, shape, and density.

• It determines the sedimentation coefficient (Svedberg unit).

• Correct match: S-2

Final Correct Combination

✅ P-3, Q-4, R-1, S-2

Option-Wise Explanation

Option (A): P-4, Q-1, R-2, S-3 ❌

• Circular dichroism does not determine tertiary structure.

• Freeze-drying does not measure sedimentation coefficient.

• ❌ Incorrect.

Option (B): P-1, Q-4, R-3, S-2 ❌

• Circular dichroism does not measure concentration.

• Freeze-drying does not determine secondary structure.

• ❌ Incorrect.

Option (C): P-2, Q-3, R-4, S-1 ❌

• Circular dichroism does not measure sedimentation coefficient.

• Ultracentrifugation does not measure concentration.

• ❌ Incorrect.

Option (D): P-3, Q-4, R-1, S-2 ✅

• All technique-application matches are scientifically accurate.

• ✅ Correct Answer.

✔ Correct Answer

Option (D)

Quick Exam Memory Trick

• CD → Secondary structure

• X-ray → 3D structure

• Freeze-drying → Concentration

• Ultracentrifugation → Sedimentation coefficient