The GATE Grind

GATE 2025 BT – Question 12

General Biology · Microbiology: Microbial diseases, host-pathogen interactions, antibiotics and resistance, two-component system, bacterial communication, viruses · 1 mark · Multiple choice

Corynebacterium diphtheriae causes diphtheria in humans, only when this bacterium is infected by

  1. phage $\beta$
  2. epsilon phage
  3. T4 phage
  4. lambda phage

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Correct answer: (A) phage $\beta$

Explanation

The diphtheria toxin gene (tox) is carried by the corynephage $\beta$. Only the lysogenic strains that carry this prophage make the toxin.