NEET Chemistry Chemistry in Everyday Life Questions Solved

A drug effective in the treatment of pneumonia, bronchitis, etc., is:
(a) streptomycin
(b) chloramphenicol
(c) penicillin
(d) sulphaguanidine

(c) Penicillin is an effective medicine for pneumonia disease.


  • Penicillins were the first antibiotic that doctors used.
  • There are several antibiotics in the penicillin class.
  • Experts credit Alexander Fleming with discovering penicillins.
  • Penicillin works by interfering with bacterial cell walls.
  • Less than 1 percent of people are dangerously allergic to penicillin.


Drugs in the penicillin class work by indirectly bursting bacterial cell walls. They do this by acting directly on peptidoglycans, which play an essential structural role in bacterial cells.

Peptidoglycans create a mesh-like structure around the plasma membrane of bacterial cells, which increases the strength of the cell walls and prevents external fluids and particles from entering the cell.

When a bacterium multiplies, small holes open up in its cell walls as the cells divide. Newly-produced peptidoglycans then fill these holes to reconstruct the walls.

Penicillins block the protein struts that link the peptidoglycans together. This prevents the bacterium from closing the holes in its cell walls.

As the water concentration of the surrounding fluid is higher than that inside the bacterium, water rushes through the holes into the cell and the bacterium bursts.

Difficulty Level:

  • 32%
  • 37%
  • 26%
  • 7%
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