Which term describes a virus that infects bacteria?

• A. Bacteriophage
• B. Virus
• C. Bacteria
• D. Plasmid

Answer: (A)

The main idea is naming a virus that targets bacteria. A bacteriophage is a virus that infects bacteria; the term literally reflects its host, bacteria, and its role in parasitizing them. Phages attach to a bacterial cell and inject their genetic material to hijack the cell's machinery for replication. While a virus is any infectious agent that can infect living cells, bacteriophage specifies the host range as bacteria. Bacteria are the cells that phages infect, not viruses. Plasmids are small circular DNA elements inside bacteria that carry genes and can be transferred between cells; they are not viruses and do not infect. So the term that best fits a virus that infects bacteria is bacteriophage.