Question 1

Which of the following best describes why RNA viruses mutate more rapidly than DNA viruses?

Accepted Answer

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

Question 2

A virus with a helical capsid, an envelope, and a segmented negative-sense RNA genome is most likely classified in which viral family?

Accepted Answer

Orthomyxoviridae

Question 3

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

Accepted Answer

Uncoating

Question 4

A patient is diagnosed with a viral infection that periodically flares up and then enters a dormant state. Which type of infection is this?

Accepted Answer

Latent persistent infection

Question 5

Which of the following is a medically important consequence of phage conversion in bacteria?

Accepted Answer

Bacteria may acquire genes encoding toxins, increasing their pathogenicity.

Question 6

Which laboratory method is most appropriate for quantifying the number of infectious bacteriophages in a sample?

Accepted Answer

Plaque assay

Question 7

Which antiviral drug mechanism is correctly matched with its target?

Accepted Answer

Oseltamivir: blocks release of influenza virions from host cells

Question 8

A virus is described as having a single-stranded, positive-sense RNA genome. What is the first step after entry into the host cell?

Accepted Answer

The viral genome is directly translated by host ribosomes.

Question 9

Which of the following best explains why antigenic shift in influenza viruses can lead to pandemics?

Accepted Answer

It creates new viral strains with novel HA and NA spikes, to which humans have little or no immunity.

Question 10

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack genetic material and cause spongiform encephalopathies.

Question 11

A virus is classified as 'naked' if it:

Accepted Answer

Lacks a lipid envelope and is released by lysing the host cell.

Question 12

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

Accepted Answer

They are glycoprotein extensions that mediate attachment to specific host cell receptors.

Question 13

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

Accepted Answer

Human papillomavirus (HPV)

Question 14

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

Accepted Answer

They may fail to detect viruses that have undergone antigenic shift.

Question 15

Which of the following best describes the lysogenic cycle of a temperate bacteriophage?

Accepted Answer

The phage genome integrates into the host genome and is replicated along with it without killing the host.

Question 16

Which of the following is a correct statement about the host range and tropism of viruses?

Accepted Answer

Host range refers to the species a virus can infect, while tropism refers to the specific tissues or cells targeted.

Question 17

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 18

Which of the following best explains why vaccines are an effective means to limit viral infections?

Accepted Answer

They train the immune system to recognize and respond to specific viral antigens.

Question 19

Which of the following is a distinguishing feature of prion diseases compared to viral diseases?

Accepted Answer

Prion diseases are caused by misfolded proteins without genetic material.

Viruses and Prions: Structure, Classification, Replication, and Clinical Aspects

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