$$RNA \xrightarrow{\text{reverse transcriptase}} DNA$$

Question 1

Which of the following best describes the replication strategy of a positive-sense single-stranded RNA (+ssRNA) virus such as poliovirus?

Accepted Answer

The viral RNA serves directly as mRNA for protein synthesis and as a template for making -ssRNA.

Question 2

A patient is diagnosed with AIDS. Which viral family is responsible for this disease, and what is a unique feature of its replication cycle?

Accepted Answer

Retroviridae; uses reverse transcriptase to synthesize DNA from its RNA genome.

Question 3

Which of the following equations best represents the process by which a retrovirus synthesizes DNA from its RNA genome?

Accepted Answer

$$RNA \xrightarrow{	ext{reverse transcriptase}} DNA$$

Question 4

Which virus family is associated with the common cold and SARS, and what is the nature of its genome?

Accepted Answer

Coronaviridae; positive-sense single-stranded RNA ($$+ssRNA)$$

Question 5

A virus is found to carry its own RNA-dependent RNA polymerase in the virion. Which type of viral genome is most likely present?

Accepted Answer

Negative-sense single-stranded RNA ($$-ssRNA)$$

Question 6

Which of the following best explains why negative-sense RNA viruses must package an RNA-dependent RNA polymerase within their virions?

Accepted Answer

Their RNA must first be transcribed into complementary positive-sense RNA before translation.

Question 7

Which of the following viruses is associated with benign tumors, warts, and cervical cancer?

Accepted Answer

Papillomavirus (family Papillomaviridae)

Question 8

A patient presents with severe diarrhea. Laboratory analysis identifies a double-stranded RNA virus. Which viral family is most likely responsible?

Accepted Answer

Reoviridae

Question 9

Which of the following best describes the replication of double-stranded RNA ($$dsRNA) $$viruses?

Accepted Answer

The $$dsRNA is $$separated, and the positive strand acts as mRNA for protein synthesis.

Question 10

Which of the following is a correct pairing of viral family and representative disease?

Accepted Answer

Orthomyxoviridae – Influenza (flu)

Question 11

Which of the following viruses is transmitted via the fecal-oral route and is a member of the Picornaviridae family?

Accepted Answer

Hepatovirus (hepatitis A)

Question 12

Which of the following best explains why retroviruses are unique among RNA viruses?

Accepted Answer

They use reverse transcriptase to synthesize DNA from their RNA genome.

Question 13

A virus is identified as having a mixed double- and single-stranded DNA genome and is associated with hepatitis B. Which family does it belong to?

Accepted Answer

Hepadnaviridae

Question 14

Which of the following is a correct sequence for the synthesis of viral proteins in a negative-sense RNA virus?

Accepted Answer

$$-ssRNA \xrightarrow{	ext{RNA-dependent RNA polymerase}} +ssRNA \xrightarrow{	ext{ribosome}} 	ext{Protein}$$

Question 15

Which of the following viruses is responsible for fever blisters and belongs to the Herpesviridae family?

Accepted Answer

Simplexvirus (Herpes type 1)

Question 16

Which of the following best describes the function of the positive-sense RNA strand in a +ssRNA virus?

Accepted Answer

It serves as mRNA to code for proteins and as a template for more viral nucleic acid.

Question 17

A patient is diagnosed with chickenpox. Which virus is responsible, and to which family does it belong?

Accepted Answer

Varicellovirus; Herpesviridae

Question 18

Which of the following best explains why the synthesis of +ssRNA in retroviruses is different from that in other +ssRNA viruses?

Accepted Answer

Retroviruses synthesize +ssRNA from a DNA intermediate using reverse transcriptase.

Question 19

Which of the following is a correct pairing of viral family and a representative disease caused by a negative-sense RNA virus?

Accepted Answer

Rhabdoviridae – Rabies

Question 20

Which of the following best describes the role of RNA-dependent RNA polymerase in the replication of RNA viruses?

Accepted Answer

It synthesizes complementary RNA strands from an RNA template.

Classification and Replication of RNA and DNA Viruses

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