A bacteriophage is a: (MCAER 2013)

✔Explanation: A bacteriophage, also known as a phage, is a virus that infects bacteria. It attaches to the bacterial cell wall and injects its genetic material, eventually killing the host bacterium.

🔑Key Points:
-A bacteriophage is a virus that infects and replicates within a bacterium.
-The term is derived from "bacteria".
-Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome.
-And may have relatively simple or complex structures.
Additional Information
-About Virus
-Virus replicates only inside the living cells of an organism.
-The study of viruses is known as virology.
-A virus can infect all types of life forms. 
-From animals and plants to microorganisms, including bacteria and archaea can be infected by the virus.