Question

define viruses in short

Answer 1

Viruses are infectious particles with a nucleic acid and protein called capsid which are metabolically active inside a living cell. They do not show any metabolism outside a host. so they are not considered living. Even the most infectious disease like AIDS is caused by an RNA virus called HIV

Answer 2

viruses are an interesting type off micro organisms . they behave like non living things when they are outside a living cell . but they behave like living organisms when they are inside host living cells such as bacteria , plants, and animal crlls and multiply.
they cna be seen through very powerful electron microscope.
diseases like polio, swine flu, AIDS, common cold are caused by viruses.