Question 1

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

Accepted Answer

They require host cell energy and machinery to replicate their genome and produce new virions.

Question 2

A scientist discovers a new infectious agent that passes through a filter, lacks cellular structure, and contains only RNA and protein. Which of the following best classifies this agent?

Accepted Answer

Virus

Question 3

Which of the following best describes the structure of a helical viral capsid?

Accepted Answer

A hollow tube formed by capsomeres surrounding the viral genome

Question 4

Which of the following is a unique feature of enveloped viruses compared to naked viruses?

Accepted Answer

They acquire a lipid-based envelope by budding from the host cell membrane.

Question 5

A patient is infected with a virus that frequently mutates its surface spike proteins, making it difficult for the immune system to recognize. Which process is responsible for these minor changes?

Accepted Answer

Antigenic drift

Question 6

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

Accepted Answer

RNA polymerases lack proofreading capabilities, leading to more errors during replication.

Question 7

A virus is found to infect only human liver cells but not other tissues or species. Which terms best describe this virus's host range and tropism?

Accepted Answer

Narrow host range, narrow tropism

Question 8

Which of the following is a potential consequence of antigenic shift in influenza viruses?

Accepted Answer

Emergence of a new viral strain with expanded host range and pandemic potential

Question 9

Which of the following best describes the lytic replication pathway of a bacteriophage?

Accepted Answer

The phage immediately hijacks the host machinery to produce new virions, resulting in host cell lysis.

Question 10

Which of the following viruses is associated with the development of cancer due to integration of its genome into host DNA?

Accepted Answer

Human papilloma virus (HPV)

Question 11

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

Accepted Answer

A single bacteriophage in the initial sample

Question 12

Which of the following diagnostic tests is most likely to detect very low levels of viral genetic material in a clinical sample?

Accepted Answer

Polymerase chain reaction (PCR)

Question 13

A patient is prescribed acyclovir for a viral infection. What is the mechanism of action of this drug?

Accepted Answer

It inhibits viral DNA replication by acting as a nucleoside analog.

Question 14

Which of the following best describes a prion?

Accepted Answer

An infectious protein that lacks genetic material

Question 15

A patient experiences recurring cold sores triggered by stress. Which type of viral infection is this an example of?

Accepted Answer

Latent persistent infection

Question 16

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

Accepted Answer

They require the sample to be a liquid and may not detect viruses that have undergone antigenic shift.

Question 17

Which of the following antiviral strategies is used as post-exposure prophylaxis for rabies and HIV?

Accepted Answer

Injection of laboratory-prepared antibodies to block viral entry

Question 18

A new virus is discovered with a segmented RNA genome. Which process could most likely lead to the emergence of a new viral strain with pandemic potential?

Accepted Answer

Antigenic shift via reassortment

Question 19

Which of the following best explains why prevention of viral diseases through vaccination is more effective than relying solely on antiviral drugs?

Accepted Answer

Vaccines train the immune system to recognize and respond to viruses before infection occurs.

Question 20

A patient’s brain tissue shows sponge-like holes upon autopsy, but no viral genetic material is detected. Which infectious agent is most likely responsible?

Accepted Answer

A prion

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

Study Guide - Practice Questions

Study Guide - Flashcards