Q.Distinguish between the living and non-living characters of viruses.

[!TLDR]

The question asks how the living and non-living characters of a virus differ.

[!ANSWER]

Outside a host cell a virus behaves as a non-living, inert chemical particle (it can even be crystallised), but once inside a living host cell it can direct the host's machinery to multiply - a living property - so viruses show characters of both states depending on whether or not they are inside a host.

A virus particle shows no signs of life when it is outside a living host cell: it does not grow, move or carry out its own metabolism, and it can be isolated and crystallised in the laboratory just like an ordinary chemical compound, as Wendell Stanley demonstrated with the Tobacco Mosaic Virus in 1935 - these are its non-living characters. However, once the same virus particle enters a suitable living host cell, it is able to take over the host's own cellular machinery and direct it to produce many new copies of the virus, a capacity for multiplication that is ordinarily regarded as a defining feature of life - this is its living character. Because a virus displays chemical, non-living behaviour on its own but living, multiplying behaviour only within a host, it is generally placed on the borderline between the living and the non-living worlds rather than clearly within either one.

[!ANSWER]

A virus is non-living (inert, crystallisable, no independent metabolism) outside a host cell, but shows a living character (the ability to multiply) once inside a suitable host cell - which is why viruses are considered to lie on the boundary between living and non-living matter.

• Describing viruses as simply 'non-living' or simply 'living' without noting that the classification depends on whether the virus is inside a host cell.
• Omitting that multiplication (a living property) happens only with the help of the host's own machinery, not independently.