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

Step 1: Understanding the Question:
This is a match-the-following question that pairs four antibiotic classes in List I with their mechanisms of action in List II, and asks for the code that correctly links each antibiotic to how it kills or inhibits bacteria.

Step 2: Key Concept or Approach:
The approach is to recall the mechanism of action of each antibiotic class individually — cell wall synthesis inhibitors, protein synthesis inhibitors, folate pathway inhibitors, and nucleic acid synthesis inhibitors — and then match each letter to the correct number rather than trying to eliminate whole answer codes at once.

Step 3: Working Through the Options:
Penicillin is a beta-lactam that binds penicillin-binding proteins and blocks the transpeptidation step of peptidoglycan cross-linking, so it inhibits cell wall synthesis, matching A with option 2. Tetracycline is a protein synthesis inhibitor that binds the 30S ribosomal subunit and blocks aminoacyl-tRNA from binding the ribosomal A site, best captured here as inhibiting RNA (aminoacyl-tRNA) binding to ribosomes, matching B with option 3. Sulphonamides are structural analogues of PABA that block folate synthesis early in the pathway; in this list's simplified terms that action is grouped under option 1, matching C with 1. Quinolones act on bacterial DNA gyrase (topoisomerase II), preventing DNA supercoiling and replication, matching D with option 4. Putting these together gives A-2, B-3, C-1, D-4. The other three codes swap at least one pairing incorrectly, such as attaching cell wall synthesis to tetracycline or DNA gyrase inhibition to penicillin, which does not fit any real antibiotic mechanism.

Step 4: Conclusion:
The correct match is A-2, B-3, C-1, D-4, so the second option is the right answer.