Which of the following is a characteristic of a virus?

• A. It contains both DNA and RNA in the same particle as its genetic material.
• B. It must replicate inside a living host cell to produce new virions.
• C. It has ribosomes and generates ATP through its own metabolism.
• D. It reproduces independently by binary fission on nutrient agar.

Answer: (B)

Verified step by step guidance

1. Understand that viruses are unique infectious agents that differ fundamentally from cellular life forms such as bacteria and eukaryotic cells.
2. Recall that viruses contain either DNA or RNA as their genetic material, but never both simultaneously within the same viral particle.
3. Recognize that viruses lack cellular structures such as ribosomes and do not carry out metabolic processes like ATP generation on their own.
4. Know that viruses cannot reproduce independently; instead, they must infect a living host cell and use the host's machinery to replicate and produce new virus particles (virions).
5. Conclude that the defining characteristic of viruses is their obligate intracellular replication, meaning they must replicate inside a living host cell to produce new virions.