Which of the following best describes a bacteriophage that only reproduces by lysing the host cell and does not integrate into the host genome?

• A. Temperate phage
• B. Cyclic phage
• C. Virulent phage
• D. Lytic phage

Answer: (D)

A bacteriophage that reproduces only by lysing the host and never integrates its genome is using the lytic life cycle. In the lytic cycle, the phage hijacks the bacterial machinery, rapidly makes many copies, assembles new virions, and then lyses the cell to release them. That direct destruction of the host, with no prophage formation, distinguishes it from temperate phages that can integrate into the host genome and replicate as a prophage during lysogeny. The term lytic phage specifically emphasizes this exclusively destructive pathway, and it aligns with the description. A cyclic phage isn’t the standard descriptor for this trait, and while virulent phage can describe phages that only lyse, the most direct label for this behavior is lytic phage.