UPSC Civil Services 2013 Prelims General Studies Paper I

Viruses have no metabolic enzymes and cannot generate their own energy. Viruses require a growth medium containing living cell therefore cannot be cultured in any synthetic medium. Viruses are transmitted from one organism to another not only by biological vectors but also by mechanical vectors.
Mechanical vector like an arthropod vecor which transmit an infective organism from one host to another but it is not essential to the life of cycle of the parasite.