Question

All of the following statements concerning virus taxonomy are true except:

A. Currently there are only 3 orders of viruses

B. Virus family names are sometimes derived from the name of an important virus within the family

C. Families are the highest taxonomic group used for viruses

D. Staining is used as a means of classification for viruses

Answer 1

The International Committee on Taxonomy of Viruses devised and implemented several rules on the naming and classification of viruses early in the 1990's. According to this committee ,

Viral classification starts at the level of order and follows as thus, with the taxon suffixes given in italics:

Order (-virales)
Family (-viridae)
Subfamily (-virinae)
Genus (-virus)
Species (-virus)

The recognition of orders is very recent and has been deliberately slow; to date, only three have been named, and most families remain unplaced.

So, option A is correct.

As far as option B is concerned, it holds true that most of the virus family names are derived from the name of the the important virus within the family. Let us look at the following examples to confirm this statement;

1.Adenoviridae - Adenovirus

2.Papovaviridae - Papillomavirus

3.Herpesvirid - HerpesSimplex Virus

4.Poxviridae-Small pox virus

5.Hepadnaviridae - Hepatitis B virus

6.Polyomaviridae - Polyoma virus

And many more.

so, option B is also correct

Next, as we see Family is not the highest taxonomic group used for viruses, there is still higher level which is ORDER, which is used by taxonomists for classification of viruses.

so, according to me, option C is incorrect.

Firstly, negative staining of viral suspensions provides detailed information of virus particles' structure. It is a technique that can be quickly performed and is able to accommodate the highest magnifications of virus particles. Secondly, ultra-thin sections of virus-infected tissues or cell cultures, combined with a positive staining technique can provide information regarding the localization of viruses inside or around cells. These two complementary techniques for investigating the structure of a virus and its parasitic life cycle.

As these kind of staining characteristics are important for determining the morphology, nature of genome etc. And you must be knowing Viruses are mainly classified by phenotypic characteristics, such as morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause.

therefore, Option D is possibly correct.

Hope this helps you !!