Question

Given below are two statements.

Statement I: Virulent phages are having lytic life cycle.

Statement II: In the temperate phages, phage DNA is integrated with host genome.

In light of the above statements, choose the correct answer from the options given below.

• A. Both Statement I and Statement II are true.
• B. Both Statement I and Statement II are false.
• C. Statement I is true but Statement II is false.
• D. Statement I is false but Statement II is true.

Hint:

Differentiate the two phage types easily: Virulent = Lytic only, whereas Temperate = Lysogenic + Lytic. The integrated phage DNA in lysogeny is called a prophage.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Bacteriophages are viruses that infect bacteria and exhibit two principal life cycles: the lytic cycle and the lysogenic cycle.
Virulent phages follow the lytic pathway, whereas temperate phages can integrate their DNA into the bacterial chromosome.
Detailed Explanation:
Statement I:
Virulent phages multiply rapidly inside the host bacterium, produce numerous progeny, and finally lyse the bacterial cell to release new phages.
This characteristic lytic cycle is the defining feature of virulent phages.
Therefore, Statement I is true.
Statement II:
Temperate phages undergo the lysogenic cycle, during which the phage DNA becomes integrated into the host bacterial genome as a prophage.
The prophage replicates along with the bacterial chromosome until it is induced to enter the lytic cycle.
Hence, Statement II is true.

Step 2: Final Answer:
Both Statement I and Statement II are true.
\[ \boxed{(A) Both Statement I and Statement II are true. \]