Question 1

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

Accepted Answer

They are obligate intracellular pathogens that lack cellular structures and cannot carry out metabolism independently.

Question 2

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

Accepted Answer

Membrane fusion or endocytosis.

Question 3

Which viral genome type is directly translated by host cell ribosomes without the need for transcription?

Accepted Answer

Single-stranded positive-sense RNA ($$ssRNA^+)$$

Question 4

Why do RNA viruses evolve faster than DNA viruses?

Accepted Answer

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

Question 5

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

Accepted Answer

Major genetic reassortment resulting in new viral strains with no residual immunity in the population.

Question 6

A patient is infected with a virus that integrates its genome into the host cell DNA and periodically produces new virions during flare-ups. Which type of infection is this?

Accepted Answer

Latent persistent infection

Question 7

Which of the following is a mechanism by which bacteriophages can make bacteria more pathogenic to humans?

Accepted Answer

Phage conversion, where prophages confer new pathogenicity factors such as toxins.

Question 8

Which laboratory method is commonly used to quantify bacteriophages in a sample?

Accepted Answer

Plaque assay, where clear zones represent lysed cells.

Question 9

Which antiviral drug class targets the reverse transcriptase enzyme in retroviruses?

Accepted Answer

Nucleoside reverse transcriptase inhibitors (NRTIs)

Question 10

A virus is found to infect only hepatic cells in humans. This specificity is referred to as:

Accepted Answer

Tropism

Question 11

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack genetic material and cause neurodegenerative diseases.

Question 12

Which diagnostic method is most sensitive for detecting viral genetic material in clinical samples?

Accepted Answer

Polymerase chain reaction (PCR)

Question 13

Which cytopathic effect is characterized by the fusion of multiple host cells into a single large cell containing multiple nuclei?

Accepted Answer

Syncytia

Question 14

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

Accepted Answer

They require the sample to be a liquid and antigens must be well characterized.

Question 15

Which of the following viruses is known to cause cancer by stimulating uncontrolled host cell division?

Accepted Answer

Human papilloma virus (HPV)

Question 16

A virus with a segmented RNA genome infects a pig that is exposed to both duck and human influenza viruses. What is the most likely outcome?

Accepted Answer

Antigenic shift resulting in a new hybrid virus with expanded host range.

Question 17

Which of the following is NOT a way Creuzfeldt-Jakob disease (CJD) can be transmitted?

Accepted Answer

Direct contact with infected plant material

Question 18

Which step in the animal virus replication pathway is unique compared to bacteriophage replication?

Accepted Answer

Uncoating of the viral capsid after entry

Question 19

Which antiviral drug is used to block viral entry into host cells and is effective against cold sores caused by HSV-1?

Accepted Answer

Docosanol

Question 20

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

Accepted Answer

Human immunodeficiency virus (HIV)

Viruses and Prions: Structure, Replication, and Clinical Aspects

Study Guide - Practice Questions

Study Guide - Flashcards