Question 1

Which of the following best explains why viruses are classified as nonliving microbes?

Accepted Answer

They are acellular and require a host cell for replication.

Question 2

A virus with a helical capsid structure would most likely appear as:

Accepted Answer

A hollow tube-like structure.

Question 3

Which of the following statements about viral envelopes is correct?

Accepted Answer

Enveloped viruses acquire their envelope by budding from the host cell membrane.

Question 4

Which feature distinguishes RNA viruses from DNA viruses in terms of their evolution?

Accepted Answer

RNA viruses mutate more rapidly due to lack of proofreading by RNA polymerases.

Question 5

A segmented RNA virus and a non-segmented RNA virus coinfect the same host cell. Which genetic event is most likely to occur?

Accepted Answer

Antigenic shift

Question 6

Which of the following best describes the process of antigenic drift in influenza viruses?

Accepted Answer

A gradual accumulation of mutations in the HA and NA spike proteins.

Question 7

Which property is NOT used by the International Committee on Taxonomy of Viruses (ICTV) to classify viruses?

Accepted Answer

Ability to metabolize glucose

Question 8

A virus that infects only human liver cells but not other human tissues or animal species is said to have:

Accepted Answer

Narrow host range and narrow tropism

Question 9

Which of the following steps is unique to animal virus replication compared to bacteriophage replication?

Accepted Answer

Uncoating of the viral capsid

Question 10

A patient is diagnosed with a chronic viral infection characterized by continuous low-level release of virions over several years. Which virus is most likely responsible?

Accepted Answer

Human immunodeficiency virus (HIV)

Question 11

Which of the following best describes the mechanism of action for nucleoside analog antiviral drugs?

Accepted Answer

They mimic normal nucleotides and halt viral nucleic acid replication.

Question 12

A laboratory is using a plaque assay to quantify bacteriophages. What does each plaque on the plate represent?

Accepted Answer

A single bacteriophage in the initial sample

Question 13

Which diagnostic method is most likely to detect very low levels of viral genetic material in a clinical sample?

Accepted Answer

Polymerase chain reaction (PCR)

Question 14

Which of the following is a correct statement about prions?

Accepted Answer

They are infectious proteins that cause transmissible spongiform encephalopathies.

Question 15

A patient develops Creutzfeldt-Jakob disease (CJD) after a corneal transplant. Which mode of transmission does this represent?

Accepted Answer

Iatrogenic

Question 16

Which of the following best explains why antiviral drugs are more difficult to develop than antibacterial drugs?

Accepted Answer

Viruses are obligate intracellular pathogens with fewer unique drug targets.

Question 17

Which of the following viruses is associated with the development of cancer in humans?

Accepted Answer

Human papillomavirus (HPV)

Question 18

A new virus is discovered with a single-stranded RNA genome that is immediately translated by host ribosomes upon entry. Which type of genome does this virus have?

Accepted Answer

ssRNA+

Question 19

Which of the following equations correctly represents the calculation of viral titer in a plaque assay?

Accepted Answer

$$	ext{Viral\ titer\ (PFU/ml)} = \frac{	ext{Number\ of\ plaques}}{	ext{Dilution\ factor} 	imes 	ext{Volume\ plated\ (ml)}}$$

Question 20

Which of the following best describes the role of reverse transcriptase in retroviral replication?

Accepted Answer

It synthesizes DNA from an RNA template.

Chapter 6 Study guide

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