Question 1

Which of the following statements best describes the size range of viral genomes compared to cellular genomes?

Accepted Answer

Viral genomes vary about 1,000-fold in size and are usually smaller than cellular genomes.

Question 2

What is the main function of the Baltimore classification scheme for viruses?

Accepted Answer

It categorizes viruses based on the relationship of their genome to mRNA production.

Question 3

Which Baltimore class of viruses is characterized by single-stranded positive-sense RNA genomes that can serve directly as mRNA?

Accepted Answer

Class IV

Question 4

A virus with a genome that must be transcribed into mRNA before translation in the host cell is most likely to be:

Accepted Answer

A Class V virus

Question 5

Which of the following is TRUE regarding the replication of retroviruses (Class VI)?

Accepted Answer

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

Question 6

Which Baltimore class is most commonly associated with viruses that infect plants?

Accepted Answer

Class II

Question 7

What is a unique feature of the genome of bacteriophage T4 that helps it evade host restriction-modification systems?

Accepted Answer

It contains modified 5-hydroxymethylcytosine instead of cytosine.

Question 8

Which of the following best describes the replication strategy of bacteriophage $\phi$X174?

Accepted Answer

Rolling circle replication producing concatemers.

Question 9

A student is studying a virus that can be released from the host cell without causing lysis, allowing the host to continue growing. Which virus is this most likely to be?

Accepted Answer

Bacteriophage M13

Question 10

Which of the following statements about viral taxonomy is correct?

Accepted Answer

Viral taxonomy uses a polyphasic approach, including phenotypic, genotypic, and phylogenetic analyses.

Question 11

Why is it difficult to construct universal phylogenetic trees for viruses?

Accepted Answer

Viruses lack ribosomal RNA and have high mutation rates.

Question 12

Which of the following is a consequence of the segmented genome of influenza virus?

Accepted Answer

It allows for antigenic shift, creating new hybrid viruses.

Question 13

Which of the following best explains why viroids are considered the smallest known pathogens?

Accepted Answer

They are small, circular, single-stranded RNA molecules lacking a protein coat.

Question 14

Which of the following is a defining feature of prions?

Accepted Answer

They are infectious proteins with no nucleic acid component.

Question 15

A virus is found to have a double-stranded DNA genome, replicate entirely in the cytoplasm, and is used as a vaccine vector. Which virus is this most likely to be?

Accepted Answer

Poxvirus

Question 16

Which of the following is TRUE about the replication of adenoviruses?

Accepted Answer

DNA replication occurs in a leading fashion on both DNA template strands.

Question 17

Which of the following best describes the role of the lambda repressor (cI protein) in bacteriophage lambda?

Accepted Answer

It represses lytic events, maintaining lysogeny.

Question 18

Which of the following is a key difference between the release of bacteriophage $\phi$X174 and M13 from their host cells?

Accepted Answer

$\phi$X174 is released by lysis, while M13 is released by extrusion without lysis.

Question 19

Which of the following is a major reason why most viral genes have no known homologs in cellular organisms?

Accepted Answer

High mutation rates and unique evolutionary pressures result in novel genes.

Viral Genomics and Diversity: Study Notes for Microbiology Students

Study Guide - Practice Questions

Study Guide - Flashcards