Question 1

Which of the following statements best explains why viruses are considered obligate intracellular pathogens?

Accepted Answer

They require host cell energy and machinery to replicate because they lack their own metabolic processes.

Question 2

A virus with a helical capsid and an envelope is most likely to enter a host cell by which mechanism?

Accepted Answer

Membrane fusion or endocytosis

Question 3

Which of the following best describes antigenic shift in influenza viruses?

Accepted Answer

A major genetic reassortment resulting from coinfection with different viral strains

Question 4

Which of the following is a plausible reason why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading capabilities, leading to higher mutation rates.

Question 5

A patient is diagnosed with a persistent viral infection that periodically flares up with symptoms and then enters a dormant phase. Which virus family is most likely responsible?

Accepted Answer

Herpesviridae

Question 6

Which of the following best describes the function of viral spikes (peplomers)?

Accepted Answer

They help viruses attach to and gain entry into specific host cells.

Question 7

A laboratory is screening old blood samples for a newly discovered virus. Which diagnostic method would be most sensitive and specific for detecting the viral genome?

Accepted Answer

Polymerase chain reaction (PCR)

Question 8

Which of the following viruses is associated with the development of cancer due to chronic inflammation rather than direct integration of viral genes into the host genome?

Accepted Answer

Hepatitis B virus

Question 9

A bacteriophage confers toxin production to a previously non-toxigenic bacterium. What is this process called?

Accepted Answer

Phage conversion

Question 10

Which of the following antiviral drugs acts by mimicking normal nucleotides and causing premature termination of viral nucleic acid synthesis?

Accepted Answer

Acyclovir

Question 11

A virus is classified as having a segmented, single-stranded RNA genome and an envelope. Which property is most useful for distinguishing it from other viruses?

Accepted Answer

Genome architecture

Question 12

Which of the following best explains why prions are not considered living organisms?

Accepted Answer

They do not contain genetic material and cannot replicate independently.

Question 13

A patient receives post-exposure prophylaxis after a potential rabies exposure. What is the mechanism of this treatment?

Accepted Answer

It provides laboratory-prepared antibodies that prevent viral entry into host cells.

Question 14

Which of the following is a limitation of ELISA and agglutination assays for viral detection?

Accepted Answer

They require the antigen to be well characterized and may miss viruses that have undergone antigenic shift.

Question 15

Which of the following best describes the process of viral budding?

Accepted Answer

The virus acquires a portion of the host cell membrane as its envelope during release.

Question 16

A new virus is discovered with a genome similar to hepatitis C virus. Vaccinated animals show a strong immune reaction to the new virus, while unvaccinated animals do not. What does this suggest?

Accepted Answer

The new virus shares antigenic determinants with hepatitis C virus.

Question 17

Which of the following is true regarding the host range and tropism of viruses?

Accepted Answer

Host range is determined by the ability of viral surface factors to bind to host cell receptors.

Question 18

Which of the following best explains why viruses are not classified into domains or kingdoms like other organisms?

Accepted Answer

They are not considered alive and do not have cellular structure.

Question 19

Which of the following is a real-world example of phage conversion increasing bacterial pathogenicity?

Accepted Answer

Corynebacterium diphtheriae producing diphtheria toxin

Question 20

Which of the following best describes the role of interferons in antiviral defense?

Accepted Answer

They signal neighboring cells to make defensive changes that limit viral entry and replication.

CH. 6 Viruses and Prions: Structure, Genetics, Replication, and Clinical Relevance

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