Which term refers to the group of infectious agents that require living host cells for replication?

Which term refers to the group of infectious agents that require living host cells for replication?

• A. Bacteria
• B. Fungi
• C. Prion
• D. Virus

Answer: (D)

Viruses are obligate intracellular parasites: they cannot reproduce unless they infect a living host cell and use the cell’s machinery to copy their genome and synthesize proteins. Because they lack the cellular machinery to replicate on their own, they depend entirely on the host cell, which is why this term correctly describes the infectious agents that require living host cells for replication. Bacteria and fungi are cellular organisms that can replicate on their own under the right conditions, so they don’t fit the description. Prions are infectious proteins that propagate by inducing misfolding of host proteins rather than by replicating a genome inside cells, so they don’t match the idea of needing a host cell’s replication machinery.

Viruses are obligate intracellular parasites: they cannot reproduce unless they infect a living host cell and use the cell’s machinery to copy their genome and synthesize proteins. Because they lack the cellular machinery to replicate on their own, they depend entirely on the host cell, which is why this term correctly describes the infectious agents that require living host cells for replication. Bacteria and fungi are cellular organisms that can replicate on their own under the right conditions, so they don’t fit the description. Prions are infectious proteins that propagate by inducing misfolding of host proteins rather than by replicating a genome inside cells, so they don’t match the idea of needing a host cell’s replication machinery.