Question 1

Which of the following statements best differentiates viruses from typical bacteria?

Accepted Answer

Viruses lack ribosomes and ATP-generating metabolism, while bacteria possess both.

Question 2

A scientist observes a virus with a helical capsid surrounded by an envelope and spikes. Which virus morphology is being described?

Accepted Answer

Enveloped helical virus

Question 3

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

Accepted Answer

Viruses contain either DNA or RNA, which may be single- or double-stranded.

Question 4

What is the primary function of the viral capsid?

Accepted Answer

To protect the viral nucleic acid and aid in attachment to host cells

Question 5

Which laboratory method is most commonly used to quantify bacteriophages?

Accepted Answer

Plaque assay, measuring plaque-forming units (PFUs)

Question 6

A virus is found to cause cancer by integrating its genetic material into the host cell’s DNA, leading to uncontrolled cell growth. What is this type of virus called?

Accepted Answer

Oncogenic virus

Question 7

Which of the following is an example of a latent viral infection?

Accepted Answer

Cold sores caused by Simplexvirus (HSV-1)

Question 8

Which of the following best describes a viroid?

Accepted Answer

A short piece of naked RNA that infects plants

Question 9

How does a prion cause disease?

Accepted Answer

By converting normal host proteins into abnormal, infectious forms

Question 10

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

Accepted Answer

The lytic cycle results in immediate lysis of the host cell, while the lysogenic cycle involves integration of phage DNA into the host genome.

Question 11

Which of the following best explains why antiviral drugs are often toxic to human cells?

Accepted Answer

Viruses use the host cell’s metabolic machinery for replication, so drugs that inhibit viral replication often harm host cells as well.

Question 12

A segmented RNA virus infects a pig that is simultaneously infected with a human and an avian influenza virus. What process can result in the emergence of a new viral subtype?

Accepted Answer

Antigenic shift

Question 13

Which of the following is NOT a typical method for identifying viruses in the laboratory?

Accepted Answer

Gram staining

Question 14

Which of the following best describes the role of spikes on enveloped viruses?

Accepted Answer

They facilitate attachment to host cell receptors and can be used for viral identification.

Question 15

Which of the following is a characteristic of persistent viral infections?

Accepted Answer

The virus is continuously released, and symptoms gradually increase over time.

Question 16

Which of the following is true regarding the cultivation of animal viruses?

Accepted Answer

They require living cells, such as animals, embryonated eggs, or cell cultures.

Question 17

Which of the following best defines a viral species?

Accepted Answer

A group of viruses sharing the same genetic information and ecological niche

Question 18

Which of the following is a correct example of viral taxonomy?

Accepted Answer

Family: Herpesviridae, Genus: Simplexvirus, Species: Human herpesvirus-2

Question 19

Which of the following statements about the human virome is correct?

Accepted Answer

The majority of the human virome consists of bacteriophages.

Question 20

Which of the following best explains why you can get influenza or COVID-19 more than once?

Accepted Answer

Antigenic drift causes mutations in viral surface proteins, allowing the virus to evade existing antibodies.

Viruses, Viroids, and Prions: Structure, Classification, and Pathogenicity

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