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GATE 2023 BT Q.25: solution and answer

GATE 2023 · BTQ.25 · 1 mark · MCQ

Match the types of RNA in Group I with their corresponding function in Group II.

Group I:
P. mRNA
Q. rRNA
R. miRNA
S. tRNA

Group II:
1. Serves as adaptors between mRNA and amino acids during protein synthesis
2. Regulates post-transcriptional gene expression
3. Codes for proteins
4. Forms the core of the ribosome structure and catalyzes protein synthesis

GATE 2023 BT question 25: A two-column matching table.Tap to open full size
Figure from the GATE 2023 BT paper. It is part of the question.
Figure description

A two-column matching table. Left column header 'Group I' lists four labeled RNA types: P. mRNA, Q. rRNA, R. miRNA, S. tRNA (each in its own row). Right column header 'Group II' lists four numbered functional descriptions in corresponding rows: 1. Serves as adaptors between mRNA and amino acids during protein synthesis; 2. Regulates post-transcriptional gene expression; 3. Codes for proteins; 4. Forms the core of the ribosome structure and catalyzes protein synthesis. The rows in Group I and Group II are not pre-aligned to each other — the candidate must determine the correct pairing.

  1. (A)

    P-3, Q-4, R-2, S-1

  2. (B)

    P-3, Q-4, R-1, S-2

  3. (C)

    P-4, Q-3, R-2, S-1

  4. (D)

    P-2, Q-1, R-4, S-3

Answer and solution

ANSWER

The correct answer is (A) P-3, Q-4, R-2, S-1.

Official answer: ASource: Official answer key, GATE 2023 BT (IIT Kanpur)

  1. mRNA (P) is the messenger transcript that carries the protein-coding sequence and is translated by ribosomes: P → 3 ("codes for proteins").

  2. rRNA (Q) is the structural scaffold of both ribosomal subunits, and its large-subunit rRNA catalyzes peptide bond formation (a ribozyme activity): Q → 4 ("forms the core of the ribosome structure and catalyzes protein synthesis").

  3. miRNA (R) base-pairs with complementary mRNA after transcription to trigger degradation or block translation: R → 2 ("regulates post-transcriptional gene expression").

  4. tRNA (S) uses its anticodon to read the mRNA codon while carrying the matching amino acid, linking codons to amino acids during translation: S → 1 ("serves as adaptor between mRNA and amino acids").

  5. Combined mapping: P-3, Q-4, R-2, S-1.

  6. Compare with options: (A) P-3, Q-4, R-2, S-1 matches exactly; (B) swaps R and S (R-1, S-2); (C) swaps P and Q (P-4, Q-3); (D) scrambles all four pairings — none of these match the derived mapping.

  7. Hence the correct choice is (A).

KEY IDEA

Each RNA class has a distinct, non-overlapping functional role: mRNA carries coding sequence, rRNA is the ribosome's structural and catalytic (ribozyme) core, miRNA post-transcriptionally silences gene expression, and tRNA is the adaptor linking codons to amino acids.

WATCH OUT FOR

Confusing tRNA's adaptor role (item 1) with miRNA's regulatory role (item 2), as in distractor (B), since both are "small" non-coding RNAs — but only tRNA physically carries amino acids and reads codons via its anticodon; miRNA acts on mRNA stability/translation, not amino acid delivery.

From the GATE 2023 BT paper. Every question of this paper · Download the full paper · All 21 Gene expression questions, with notes

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