Botany - Biological Classification Question with Solution | TestHub

Viruses are obligate parasites (holoparasites) i.e. they cannot complete its life-cycle without exploiting a suitable host. Viruses are also called Nucleoprotein i.e. they have only genetic material (nucleic acids) enclosed within a capsid (protein coat). But, the infective constituent of a virus is its genetic material i.e., DNA or RNA. Only genetic material enters into the host cell, the protein coat remains outside the host cell.

Viroids lacks the protein coat and have only the genetic material (RNA). Prions are infectious proteins.