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GATE 2026 BT Q.37: solution and answer

GATE 2026 · BTQ.37 · 2 marks · MCQ

Match the immunological terms in Column I with their function/description in the Column II. Column I: P. J gene; Q. Cyclosporin; R. Epitope; S. Hapten. Column II: 1. Suppresses immune system by blocking calcineurin; 2. Antibody binding site on a large molecule; 3. Small foreign molecule which elicits an immune response only when combined with a carrier molecule; 4. Contributes to antibody diversity.

  1. (A)

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

  2. (B)

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

  3. (C)

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

  4. (D)

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

See the question in the paper
GATE 2026 BT question 37Tap to open full size

Answer and solution

ANSWER

The correct matching is P-4; Q-1; R-2; S-3, option (C).

Official answer: CSource: Official answer key, GATE 2026 BT (IIT Guwahati)

  1. P, the gene. The , and gene segments of the immunoglobulin genes are joined by somatic recombination. Which segments are chosen, and the imprecise joining at their ends, add to antibody diversity. So P matches 4.

  2. Q, cyclosporin. It binds cyclophilin, and this complex inhibits calcineurin. Calcineurin is the phosphatase that activates NFAT, so IL-2 transcription and T-cell activation are blocked and the immune system is suppressed. So Q matches 1.

  3. R, epitope. An epitope is the part of an antigen that an antibody (or a T-cell receptor) recognises. It is the antibody binding site on a large molecule. So R matches 2.

  4. S, hapten. A hapten is a small foreign molecule that is not immunogenic alone. It elicits an immune response only when coupled to a carrier molecule such as a protein. So S matches 3.

  5. Result. P-4; Q-1; R-2; S-3, which is option (C).

  6. Other options. (A) fails because P-3, Q-4 and S-1 are wrong. (B) fails because P-2, Q-4 and R-1 are wrong. (D) fails because every pairing in it is wrong (P-1, Q-3, R-4, S-2).

KEY IDEA

Match each term to its defining role: the J segment is part of the V(D)J recombination that diversifies antibodies, cyclosporin blocks calcineurin, an epitope is the antibody-binding site on an antigen, and a hapten is a small molecule that is immunogenic only when attached to a carrier.

WATCH OUT FOR

Mixing up epitope and hapten (both relate to antibody binding), or linking the J gene with a suppressive role because it sounds like a regulatory element. The J segment is a diversity-generating gene segment, not an immunosuppressant target.

From the GATE 2026 BT paper. Every question of this paper · Download the full paper · All 6 Immune system questions, with notes

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