Question 1

Which of the following best explains why viruses are considered nonliving pathogens?

Accepted Answer

They are acellular and obligate intracellular pathogens, lacking metabolic processes for replication.

Question 2

A scientist is studying a virus with a helical capsid and an envelope. Which of the following viruses is most likely to fit this description?

Accepted Answer

Influenza virus

Question 3

Which laboratory method is most appropriate for detecting viral RNA in a patient sample suspected of SARS-CoV-2 infection?

Accepted Answer

Reverse transcription PCR (rt-PCR)

Question 4

A virus undergoes antigenic shift, resulting in a new strain that infects humans. What is the most likely consequence of this event?

Accepted Answer

A pandemic may occur due to lack of immune protection in the population.

Question 5

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause transmissible spongiform encephalopathies.

Question 6

A patient is diagnosed with a persistent viral infection that is associated with cancer. Which virus is most likely responsible?

Accepted Answer

Human papilloma virus (HPV)

Question 7

Which step in the viral replication cycle is targeted by nucleoside analog antiviral drugs?

Accepted Answer

Replication (synthesis of nucleic acids)

Question 8

A bacteriophage infects a bacterial cell and integrates its genome into the host chromosome, remaining dormant until stress triggers its activation. What is this process called?

Accepted Answer

Lysogenic replication

Question 9

Which of the following best describes the host range of a virus?

Accepted Answer

The collection of species a virus can infect.

Question 10

A researcher observes that a virus has a segmented RNA genome and frequently undergoes reassortment events. Which virus is most likely being studied?

Accepted Answer

Rotavirus

Question 11

Which of the following is a limitation of agglutination tests and ELISAs for viral detection?

Accepted Answer

They require well-characterized antigens and may not detect viruses that have undergone antigenic shift.

Question 12

Which viral genome type requires reverse transcriptase for replication?

Accepted Answer

Single-stranded RNA (ssRNA) retrovirus

Question 13

A patient sample is tested for antibodies against a viral protein using latex agglutination. What does a positive result indicate?

Accepted Answer

The patient has had prior exposure to the virus.

Question 14

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

Accepted Answer

RNA polymerases lack proofreading capabilities.

Question 15

Which of the following is a real-world consequence of phage conversion in bacteria?

Accepted Answer

Bacteria gain new pathogenic properties, such as toxin production.

Question 16

A virus is classified as having a broad tropism. Which of the following is most likely true?

Accepted Answer

It infects multiple tissue types within a host.

Question 17

Which of the following equations correctly represents the calculation of viral titer using plaque-forming units (PFUs)?

Accepted Answer

$$PFU = \frac{	ext{Number of plaques}}{	ext{Volume of sample (mL)}}$$

Question 18

Which antiviral drug mechanism involves short nucleotide sequences binding to viral RNA to inhibit translation?

Accepted Answer

Antisense antivirals

Question 19

A patient is infected with a virus that enters the host cell via membrane fusion. Which type of virus is most likely responsible?

Accepted Answer

Enveloped virus

Question 20

Which of the following is a medically important consequence of persistent viral infections?

Accepted Answer

They can lead to chronic diseases and cancer.

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

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