Question

Match the immunological terms in Column I with their function/description in Column II.

Column I	Column II
P. J gene	1. Suppresses immune system by blocking calcineurin
Q. Cyclosporin	2. Antibody binding site on a large molecule
R. Epitope	3. Small foreign molecule which elicits immune response only when combined with a carrier molecule
S. Hapten	4. Contributes to antibody diversity

• A. P-3; Q-4; R-2; S-1
• B. P-2; Q-4; R-1; S-3
• C. P-4; Q-1; R-2; S-3
• D. P-1; Q-3; R-4; S-2

Hint:

Match each immunology term to its one-line definition; cyclosporin and haptens are the easiest to fix first.

Answer 1

The Correct Option is C

This question checks basic immunology vocabulary. Go through each term in Column I and match it to the one description in Column II that actually describes it.

1. P. J gene: the J (joining) gene segments are one of the segments (along with V, D and C) that get shuffled and joined together during antibody gene rearrangement. This joining process is what generates a huge number of different antibody sequences from a small set of gene segments, so the J gene contributes to antibody diversity. This matches description 4.
2. Q. Cyclosporin: cyclosporin (cyclosporine A) is an immunosuppressant drug used after organ transplants. It binds a protein called cyclophilin, and this complex blocks the enzyme calcineurin inside T cells. Calcineurin is needed to switch on the IL-2 gene, so blocking it stops T cell activation and suppresses the immune system. This matches description 1.
3. R. Epitope: an epitope is the small, specific part of a large antigen (protein, polysaccharide, etc.) that an antibody or a T cell receptor physically binds to. In other words, it is the antibody binding site on a large molecule. This matches description 2.
4. S. Hapten: a hapten is a small chemical group that can bind an antibody once one has formed, but is too small on its own to trigger an immune response. It only becomes immunogenic once it is chemically attached to a larger carrier protein. This matches description 3.

Putting the four matches together: P-4, Q-1, R-2, S-3. Checking the given options, this combination is exactly option (C).

Let's summarize:

• J gene segments diversify antibodies through gene rearrangement.
• Cyclosporin suppresses immunity by blocking calcineurin in T cells.
• An epitope is the actual binding site an antibody recognizes on an antigen.
• A hapten needs a carrier molecule before it can trigger an immune response.

So the correct match is P-4; Q-1; R-2; S-3, which is option (C).