Question

Which of the following statements are correct:
A. Heterokaryosis is the main feature of Bacteria
B. Parasexuality is a method for creating variability in some fungi
C. Variability is common in smut fungi
D. In bacteria variability is created by conjugation
E. virulence is lost due to repeated sub-culturing

• A. A, B, D, E only
• B. B, C, D, E only
• C. A, B, C, D only
• D. B, C, D only

Hint:

"Heterokaryon" refers to different nuclei. Only eukaryotes (like Fungi) have a defined nucleus; bacteria are prokaryotes and cannot be heterokaryotic.

Answer 1

The Correct Option is B

Concept: Pathogens use various mechanisms to generate genetic diversity, which is essential for overcoming host resistance and environmental stress.

Step 1: Evaluate Bacteria-related statements (A and D).
Heterokaryosis (A) is the presence of genetically different nuclei in the same cell, which is a feature of Fungi, not bacteria. Therefore, Statement A is incorrect. Statement D is correct: Bacteria create variability through horizontal gene transfer methods like conjugation, transformation, and transduction.

Step 2: Evaluate Fungi-related statements (B and C).
Statement B is correct: Parasexuality is a non-sexual mechanism for genetic recombination in some fungi. Statement C is correct: Smut fungi (Ustilaginales) are known for high variability, often leading to the breakdown of resistant crop varieties.

Step 3: Evaluate Statement E.
Statement E is correct: Virulence (the degree of pathogenicity) often decreases or is lost when a pathogen is grown repeatedly on artificial media (sub-culturing) because the pressure to maintain infection mechanisms is removed.