Viruses are the intermediate between living and non-living entities. They resemble non-living objects in:
(a) Lacking protoplast.
(b) Ability to get crystallized, e.g., TMV, poliomyelitis virus.
Inability to live independent of a living cell.
(d) High specific gravity which is found only in non-living objects.
(e) Absence of respiration. Absence of energy storing system.
(f) Absence of growth and division.
Viruses resembles living beings which are as follows:
(a) It is formed of organic macromolecules, which occur only in living beings.
(b) Presence of genetic material.
(c) Ability to multiply or reproduce.
(d) Occurrence of mutations. The most mutable virus is HIV or AIDS.
(e) Occurrence of enzyme transcriptase in most viruses.
(f) They breed true to their type. Even variations are inheritable.
(g) They take over biosynthetic machinery of the host cell and produce chemicals required for multiplication.