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 metabolic enzymes and ribosomes.

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 in the laboratory?

Accepted Answer

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

Question 3

Which of the following best describes the structure of a nonenveloped polyhedral virus?

Accepted Answer

A protein capsid composed of capsomeres forming many-sided (icosahedral) shapes, with no lipid envelope.

Question 4

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 and death of the host cell, while the lysogenic cycle involves integration of phage DNA into the host genome as a prophage.

Question 5

A virus with a single-stranded RNA genome that serves directly as mRNA for protein synthesis belongs to which group?

Accepted Answer

Single-stranded RNA, positive-sense (+) strand viruses

Question 6

Which of the following best explains why most antiviral drugs are toxic to host cells?

Accepted Answer

Viruses use the host cell's metabolic machinery for replication, so drugs that inhibit viral replication often also harm host cell functions.

Question 7

Which of the following is a characteristic unique to prions compared to viruses and viroids?

Accepted Answer

They contain only protein and no nucleic acid.

Question 8

A patient is diagnosed with cervical cancer caused by a viral infection. Which viral family is most likely responsible?

Accepted Answer

Papovaviridae (Human papillomavirus)

Question 9

Which of the following steps is NOT part of the lytic replication cycle of a T-even bacteriophage?

Accepted Answer

Integration of phage DNA into the host genome

Question 10

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

Accepted Answer

A prophage excises from the host genome, carrying adjacent bacterial genes to a new host cell.

Question 11

Which of the following is a correct statement about the taxonomy of viruses?

Accepted Answer

Genus names end in -virus, family names end in -viridae, and order names end in -ales.

Question 12

Which of the following laboratory techniques would be most useful for identifying a virus based on its reaction with specific antibodies?

Accepted Answer

Western blotting

Question 13

A virus is found to have a lipid envelope with glycoprotein spikes. What is the most likely function of these spikes?

Accepted Answer

Attachment to specific receptors on host cells

Question 14

Which of the following best describes a latent viral infection?

Accepted Answer

The virus remains dormant in the host cell for long periods and may reactivate later.

Question 15

Which of the following is a real-world example of a persistent viral infection?

Accepted Answer

HIV/AIDS, where the virus is continuously released and causes gradual immune system decline.

Question 16

Which of the following is true regarding the genome of viruses?

Accepted Answer

A virus may have either DNA or RNA, but never both.

Question 17

Which of the following best explains how a protein can be infectious, as in the case of prions?

Accepted Answer

An abnormal prion protein (PrPSc) induces normal prion proteins (PrPC) to misfold, leading to disease.

Question 18

Which of the following is a correct pairing of a virus family and a disease it causes?

Accepted Answer

Rhabdoviridae – Rabies

Question 19

A plant pathologist discovers a new infectious agent that consists only of a short piece of naked RNA and causes disease in potatoes. This agent is best classified as a:

Accepted Answer

Viroid

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

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