Q.14 Match the entries in Group I with the entries in Group II

The correct matching is: P‑3, Q‑4, R‑2, S‑1, so the right option is (C).

Introduction

This MCQ asks to match classic discoveries in molecular biology and origin‑of‑life research with the scientists who performed the key experiments. Understanding which experiment established DNA replication mechanism, cracked the genetic code, simulated early Earth chemistry and proved DNA as genetic material is essential for competitive exams in life sciences.​

Correct matching explained

Group I:

• P) DNA replication

• Q) Genetic code

• R) Life on Earth

• S) DNA as Genetic material

Group II:

1. Hershey and Chase

2. Miller and Urey

3. Meselson and Stahl

4. Nirenberg and Khorana

The correct pairs are:

• P) DNA replication → 3) Meselson and Stahl

• Q) Genetic Code → 4) Nirenberg and Khorana

• R) Life on Earth → 2) Miller and Urey

• S) DNA as Genetic material → 1) Hershey and Chase

So, option (C) P‑3, Q‑4, R‑2, S‑1 is correct.

Why each pair is correct

P) DNA replication – Meselson and Stahl (3)

• Meselson and Stahl used 15N15N and 14N14N labeled DNA in E. coli and density‑gradient centrifugation to demonstrate that DNA replication is semi‑conservative, where each daughter molecule has one parental and one new strand.​

• Their experiment is widely described as “the most beautiful experiment in biology” and is the classic reference whenever an exam mentions experimental proof of the mechanism of DNA replication.​

Q) Genetic code – Nirenberg and Khorana (4)

• Marshall Nirenberg and Har Gobind Khorana used synthetic RNA templates (like poly‑U, poly‑UC and defined repeating sequences) in cell‑free systems to assign specific codons to amino acids, thereby deciphering the genetic code.​

• Their work showed that mRNA is read in triplet codons and mapped nearly all 64 codons, for which they shared the 1968 Nobel Prize in Physiology or Medicine.​

R) Life on Earth – Miller and Urey (2)

• Stanley Miller and Harold Urey performed a classic origin‑of‑life experiment in 1952 by simulating early Earth atmosphere (water, methane, ammonia, hydrogen) subjected to electric sparks and obtained amino acids and other organic compounds.​

• This experiment supported the Oparin–Haldane hypothesis that organic molecules necessary for life could arise abiotically under primitive Earth conditions, linking them directly to “life on Earth” questions in exams.​

S) DNA as genetic material – Hershey and Chase (1)

• Hershey and Chase infected bacteria with bacteriophages labeled with radioactive sulfur in proteins or radioactive phosphorus in DNA, then used a blender and centrifugation to track which label entered cells.​

• They found that radioactive DNA, not protein, entered the bacteria and directed phage production, conclusively showing that DNA is the genetic material in phages and strongly supporting DNA as the universal hereditary material.​

Option‑wise analysis

Option (A): P‑2, Q‑1, R‑3, S‑4 – Incorrect

• P‑2 wrongly links DNA replication with Miller and Urey, who worked on chemical evolution, not replication mechanisms.​

• Q‑1 incorrectly assigns the genetic code to Hershey and Chase; they demonstrated DNA as genetic material instead.​

• R‑3 wrongly attributes “life on Earth” to Meselson and Stahl, whose work focused on replication, not abiogenesis.​

• S‑4 incorrectly connects DNA as genetic material to Nirenberg and Khorana, who decoded the codon–amino acid relationship rather than proving DNA’s hereditary role.​

Option (B): P‑4, Q‑3, R‑2, S‑1 – Incorrect

• P‑4 claims Nirenberg and Khorana discovered DNA replication, but their contribution was deciphering the genetic code, not replication.​

• Q‑3 assigns genetic code to Meselson and Stahl, who dealt with replication, not codon assignments.​

• R‑2 is correct (Miller and Urey – life on Earth), and S‑1 is correct (Hershey and Chase – DNA as genetic material).​

• Because two pairings (P and Q) are wrong, this option is overall incorrect.

Option (C): P‑3, Q‑4, R‑2, S‑1 – Correct

• P‑3 correctly matches Meselson and Stahl with DNA semi‑conservative replication.​

• Q‑4 correctly matches Nirenberg and Khorana with deciphering the genetic code.​

• R‑2 correctly matches Miller and Urey with origin‑of‑life chemical evolution experiments.​

• S‑1 correctly matches Hershey and Chase with DNA as the genetic material.​

Option (D): P‑3, Q‑4, R‑1, S‑2 – Incorrect

• P‑3 and Q‑4 are both correct as above.​

• R‑1 wrongly links life on Earth with Hershey and Chase, whose experiments involved bacteriophages, not abiogenesis.​

• S‑2 wrongly claims DNA as genetic material was proven by Miller and Urey, whose work focused on prebiotic synthesis, not heredity.​

Key takeaway for exams

• Remember this high‑yield mapping: Meselson & Stahl – DNA replication; Nirenberg & Khorana – genetic code; Miller & Urey – origin of life; Hershey & Chase – DNA as genetic material.​

• Questions that say “Match the entries in Group I with the entries in Group II” on these four topics almost always expect this exact pairing, making option elimination straightforward once each experiment is clearly associated with its discovery.