Final answer:
The statement 'Viruses can replicate on the head of a pin' is false since viruses need to infect a host cell to replicate, using the cell's machinery. The replication process varies with bacteriophages doing so in the cytoplasm of prokaryotic cells and most DNA viruses in the nucleus of eukaryotic cells.
Step-by-step explanation:
The statement 'Viruses can replicate on the head of a pin' is false. Viruses require a host cell to replicate because they lack the necessary machinery to carry out metabolic processes and protein synthesis on their own. A virus is an acellular entity consisting of genetic material (DNA or RNA) surrounded by a protein coat, and it must infect a living cell to use that cell's ATP, ribosomes, enzymes, and other cellular parts for replication.
All viruses depend on cells for reproduction. Bacteriophages, for example, replicate only in the cytoplasm of prokaryotic cells, while most DNA viruses in eukaryotic cells replicate inside the nucleus, with notable exceptions like the poxviruses that replicate in the cytoplasm. RNA viruses usually replicate in the cytoplasm as well, except some like the Influenza virus.