Correct answer: Option (C) – P-4, Q-1, R-2, S-3.
RNase P is a ribozyme, RNA polymerase I transcribes rRNA genes, siRNA mediates gene silencing, and guide RNA directs Cas9‑mediated genome editing.​

Introduction

This question tests the ability to match major RNA‑related molecules from Column I with their precise properties or functions in Column II, a favorite theme in CSIR‑NET, GATE and other life‑science exams. Understanding what RNase P, RNA polymerase I, siRNA and guide RNA actually do in the cell makes such matching questions straightforward.​

Step‑wise matching of Column I and Column II

RNase P (P)

• RNase P is an essential endoribonuclease that removes the 5′ leader sequence from precursor tRNAs, producing mature tRNA.​

• Its catalytic component is an RNA molecule, making RNase P a classic ribozyme.​

So, P matches with 4. Ribozymes.

RNA polymerase I (Q)

• RNA polymerase I (Pol I) is a eukaryotic nuclear RNA polymerase specialized for transcription of ribosomal RNA (rRNA) genes from rDNA.​

• It synthesizes the large rRNA precursor (for example 45S pre‑rRNA in mammals), not tRNA or mRNA.​

So, Q matches with 1. rRNA gene transcription.

siRNA (R)

• Small interfering RNA (siRNA) is a short double‑stranded RNA that becomes part of the RNA‑induced silencing complex (RISC).​

• The RISC–siRNA complex binds complementary mRNA and cleaves or degrades it, causing sequence‑specific gene silencing at the post‑transcriptional level.​

So, R matches with 2. Gene silencing.

Guide RNA (S)

• In CRISPR–Cas9 systems, the single‑guide RNA (sgRNA or guide RNA) contains a sequence complementary to the target DNA and directs Cas9 to that site.​

• Once bound, Cas9 generates a double‑strand break at the target, enabling precise Cas9‑mediated genome editing via non‑homologous end joining or homology‑directed repair.​

So, S matches with 3. Cas9‑mediated genome editing.

Evaluation of all options

Option (A): P–4; Q–5; R–2; S–3

• P–4 is correct: RNase P is a ribozyme.​

• Q–5 is wrong: tRNA genes are transcribed mainly by RNA polymerase III, not RNA polymerase I.​

• R–2 and S–3 are correct, but one incorrect pair makes the whole option invalid.

Conclusion: Option (A) is incorrect.

Option (B): P–5; Q–1; R–3; S–4

• P–5 is wrong: RNase P processes tRNA precursors but does not transcribe tRNA genes.​

• R–3 is wrong: Cas9‑mediated genome editing is directed by guide RNA, not siRNA.​

Conclusion: Option (B) is incorrect.

Option (C): P–4; Q–1; R–2; S–3

• P–4: RNase P is a ribozyme.​

• Q–1: RNA polymerase I carries out rRNA gene transcription.​

• R–2: siRNA causes gene silencing.​

• S–3: guide RNA directs Cas9‑mediated genome editing.​

Conclusion: All matches are correct, so Option (C) is the right answer.

Option (D): P–1; Q–3; R–4; S–2

• P–1 is wrong: RNase P does not perform rRNA transcription.​

• Q–3 is wrong: RNA polymerase I is not involved in Cas9 genome editing.​

Conclusion: Option (D) is incorrect.

Quick reference table

This structure aligns the molecules in Column I with their correct properties or functions in Column II, fulfilling the requirement to match the molecules in column I with their correct property or function in column II for competitive exam preparation.​