Viruses And Subviral Particles

Viruses are non-cellular particulate entities. They cause various disease in living organisms. The only point favouring the virus as living entities is that they have the ability to reproduce (multiply) within the host by using host's machinery. The only point favouring the viruses as living entities is that they have the ability to reproduce (multiply)-though in the host using host's machinery.

1971 T.O.Diener discovered viroids which are infectious agents. They consist of very low molecular weight RNA without any protein coat. These are smaller than viruses that cause potato spindle tuber disease chrysanthemum stunt etc.

Answer (a) Lichens do not grow in polluted areas.