Question

Viruses are non-cellular organisms but replicate themselves once they infect the host cell. To which of the following kingdoms do viruses belong?
A. Monera
B. Protista
C. Fungi
D. None of the above

Answer 1

Hint: Viruses are typical non-cellular, microscopic infectious agents that can only replicate inside/under a host cell. In fact, they have certain defining characteristic features of living organisms and nonliving entities.

Complete answer: Viruses are called to be a connecting link between the living and nonliving organisms. So, they do not belong to any of these kingdoms. Viruses can be grouped mainly on their phenotypic characteristics, core content, chemical composition, capsid structure, size, shape, genome structure, and modes of replication. The Baltimore classification is the most generally used for studying the system of virus classification. This system was developed or created by an American biologist David Baltimore in the 1970s, for which he got the Nobel Prize.
Hence, the correct answer is Option D

Note: Some important points of viruses are listed below:
-Non-cellular organisms and enclosed in a protective envelope.
-The existence of spikes helps in attaching the viruses to the host cell.
-They do not grow.
-They neither respire nor metabolize, but they reproduce.
-They are surrounded by a protein coat-capsid and possess a nucleic acid core comprising DNA or RNA.
-They are examined both as living and non-living. They remain inactive when they are present outside of host cells, but become active inside host cells. These viruses cause many infections and reproduce within the host cell by using the enzymes and raw materials.