Question

Which statement among A-D is false regarding non-retrovirus RNA viruses?

A. they possess RNA-dependent RNA polymerase

B. the genome of single stranded (+) RNA virus like West Nile virus, can serve directly as mRNA

C. during the multiplication process inside a host cell, a single stranded (-) RNA virus must go through a (+) RNA stage before forming progeny phage

D. such viruses can produce a provirus form in the host E. None of A-D is false, they are all true statements

Answer 1

non-retroviruses are RNA viruses which has RNA as the genetic material but they lack reverse transcriptase enzyme.

the genetic material can be either + strand RNA, - strand RNA or double-stranded RNA.

+ stranded RNA can be directly translated, and they have RNA dependent RNA polymerase which produces - strand RNA from + strand RNA, then -strand RNA is used to make multiple copies of + strand RNA.

West Nile virus has + strand RNA as the genetic material.

If the genetic material is - strand RNA, it cannot be translated so RNA dependent RNA polymerase produces + strand RNA from -strand RNA.

In retroviruses the DNA is produced from RNA using reverse transcriptase enzyme then it is integrated to host genome to form provirus, so the answer is  D. such viruses can produce a provirus form in the host