Organise a discussion in your class on the topic – Are viruses living or nonliving?

Viruses are regarded as intermediate between non-living entities and living organisms. It is very difficult to ascertain whether they are living or non- living. Some characters of viruses suggest their non-living nature whereas many other characters suggest their living nature.

They resemble non-living objects in

(i) Lacking protoplast.

(ii) Ability to get crystallized.

(iii) Inability to live independent of living cell.

(iv) High specific gravity which is found only in non-living objects.

(v) Absence of respiration.

(vi) Absence of energy storing system.

(vii) Absence of growth and division. Instead, different parts are synthesized separately.

Viruses resemble living beings in

(i) Being formed of organic macromolecules which occur only in living beings.

(ii) Presence of genetic material.

(iii) Ability to multiply or reproduce although only inside living cell.

(iv) Occurrence of mutations.

(v) Occurrence of enzyme transcriptase in most viruses.

(vi) Some viruses like Pox virus contain vitamins like riboflavin and biotin.

(vii) Infectivity and host specificity.

(viii) Viruses are ‘killed’ by autoclaving and ultraviolet rays.

(ix) They breed true to their type. Even variations are inheritable.

(x) They take over biosynthetic machinery of the host cell and produce chemicals required for their multiplication.

(xi) Viruses are responsible for a number of infectious’ diseases like common cold, epidemic influenza, chicken pox.