Answer:
Viruses can only replicate themselves by infecting a host cell and therefore cannot reproduce on their own. ... A primary reason is that viruses do not possess a cell membrane or metabolise on their own - characteristics of all living organisms. Viruses are non living and cannot reproduce on their own. Viruses lack most of the characteristics of living things. The aerage virus is large when compared with cells. Viruses can cause or help to prevent and treat disease.