Question

Match List I (Antibiotic) with List II (Mechanism of Action) and select the correct answer using the codes given below the lists:

List I (Antibiotic)	List II (Mechanism of Action)
A. Penicillin	1. Inhibit dihydrofolate reductase
B. Tetracycline	2. Inhibit cell wall synthesis
C. Sulphonamide	3. Inhibit RNA binding to ribosomes
D. Quinolone	4. Inhibit DNA gyrase

• A. A-2, B-1, C-3, D-2
• B. A-2, B-3, C-1, D-4
• C. A-4, B-1, C-3, D-2
• D. A-4, B-3, C-1, D-2

Hint:

Match each antibiotic to its own step in bacterial physiology: cell wall, ribosome, folate pathway, or DNA replication.

Answer 1

The Correct Option is B

This question tests whether you can pair four antibiotic classes with their true mechanism of action rather than just recognising the drug names.

1. A-2, B-1, C-3, D-2: wrong — it repeats "2" for both A and D, which cannot be right since penicillin and quinolones work through completely different mechanisms.
2. A-2, B-3, C-1, D-4: correct — penicillin blocks cell wall synthesis (2), tetracycline blocks ribosomal binding (3), sulphonamide interferes with the folate pathway (1), and quinolone inhibits DNA gyrase (4).
3. A-4, B-1, C-3, D-2: wrong — it assigns DNA gyrase inhibition to penicillin, which is actually a cell-wall-acting drug, not a nucleic-acid-acting one.
4. A-4, B-3, C-1, D-2: wrong — it assigns cell wall synthesis inhibition to quinolone, but quinolones act on DNA gyrase, not the cell wall.

Correct answer: A-2, B-3, C-1, D-4.