Question 1

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

Accepted Answer

They require living host cells to multiply because they lack ribosomes and an ATP-generating mechanism.

Question 2

A scientist is attempting to culture a newly discovered virus. Which of the following methods would be most appropriate for growing animal viruses for vaccine development?

Accepted Answer

Injecting the virus into embryonated eggs and observing changes or death of the embryo.

Question 3

Which of the following best describes the genetic material found in viruses?

Accepted Answer

Viral genomes may be single- or double-stranded DNA or RNA, but never both in the same virion.

Question 4

A patient is diagnosed with a persistent viral infection that gradually worsens over years and is ultimately fatal. Which of the following viruses is most likely responsible?

Accepted Answer

Measles virus causing subacute sclerosing panencephalitis

Question 5

Which of the following is a key difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in the immediate lysis of the host cell, while the lysogenic cycle involves integration of phage DNA as a prophage and does not immediately kill the host.

Question 6

Which of the following best explains why naked (nonenveloped) viruses are generally more resistant to environmental stresses such as drying and detergents than enveloped viruses?

Accepted Answer

Naked viruses lack an envelope, making them less susceptible to disruption by detergents and environmental factors.

Question 7

A laboratory is using the plaque method to quantify bacteriophages. What does each plaque observed on the bacterial lawn represent?

Accepted Answer

A single virus particle (virion) that has infected and lysed bacterial cells.

Question 8

Which of the following is a correct pairing of viral family, genus, and common name?

Accepted Answer

Family: Herpesviridae; Genus: Simplexvirus; Common name: Herpes simplex virus

Question 9

Which of the following laboratory techniques would be most useful for specifically identifying the presence of influenza virus in a patient sample?

Accepted Answer

ELISA (enzyme-linked immunosorbent assay)

Question 10

A virus is found to have a single-stranded RNA genome of negative polarity. Which enzyme must this virus carry or encode to successfully replicate in a host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 11

Which of the following best describes the process of specialized transduction?

Accepted Answer

A lysogenic phage transfers specific bacterial genes adjacent to the prophage to another bacterium during excision.

Question 12

Which of the following is a characteristic of a transformed cell resulting from viral oncogenesis?

Accepted Answer

It harbors a tumor-specific transplantation antigen (TSTA) on its surface and may be irregularly shaped.

Question 13

A patient presents with cold sores that recur during periods of stress. Which type of viral infection does this represent, and which virus is most likely responsible?

Accepted Answer

Latent infection; herpes simplex virus type 1 (HHV-1)

Question 14

Which of the following best explains how an RNA virus such as HTLV-1 can cause cancer in humans?

Accepted Answer

By using reverse transcriptase to produce DNA from its RNA genome, which then integrates into the host DNA.

Question 15

Which of the following statements about prions is correct?

Accepted Answer

Prions are misfolded proteins that can induce normal proteins to misfold, leading to diseases such as Creutzfeldt-Jakob disease.

Question 16

Which of the following best describes the function of viral spikes?

Accepted Answer

They are projections made of carbohydrate and protein that may be used for attachment to host cells.

Question 17

A virus is classified as a member of the family Coronaviridae. Which of the following characteristics is most likely true for this virus?

Accepted Answer

It is a single-stranded RNA, positive-sense, enveloped virus.

Question 18

Which of the following is a practical advantage of using continuous cell lines over primary cell lines for culturing animal viruses?

Accepted Answer

Continuous cell lines can be maintained indefinitely, providing a consistent source of host cells.

Question 19

Which of the following steps is unique to the multiplication of animal viruses compared to bacteriophages?

Accepted Answer

Uncoating of the viral nucleic acid from the capsid by host or viral enzymes.

Chapter 13: Viruses, Viroids, and Prions – Structure, Taxonomy, and Multiplication

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