Question 1

Which of the following best explains why viruses are classified as nonliving microbes?

Accepted Answer

They lack a cellular structure and cannot replicate independently.

Question 2

A virus with a helical capsid and a lipid envelope is most likely to enter a host cell by which mechanism?

Accepted Answer

Membrane fusion

Question 3

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be composed of either DNA or RNA, which may be single or double stranded.

Question 4

Why do RNA viruses generally evolve faster than DNA viruses?

Accepted Answer

RNA-dependent RNA polymerases lack proofreading activity.

Question 5

Which process is responsible for the emergence of new influenza virus subtypes that can cause pandemics?

Accepted Answer

Antigenic shift

Question 6

A virus is described as having a broad tropism. What does this mean?

Accepted Answer

It can infect a wide variety of tissues or cell types within a host.

Question 7

Which of the following is a correct sequence of steps in the generalized animal virus replication pathway?

Accepted Answer

Attachment → Penetration → Uncoating → Replication → Assembly → Release

Question 8

Which laboratory method is used to quantify the number of infectious viral particles in a sample?

Accepted Answer

Plaque assay

Question 9

A patient is diagnosed with a chronic viral infection. Which of the following best describes this type of infection?

Accepted Answer

The virus is continuously released over time, often with slow disease progression.

Question 10

Which antiviral drug mechanism is correctly matched with its target?

Accepted Answer

Acyclovir: inhibits viral DNA replication

Question 11

Which of the following viruses is associated with the development of cervical cancer?

Accepted Answer

Human papilloma virus (HPV)

Question 12

Which of the following best describes a prion?

Accepted Answer

An infectious protein that lacks genetic material

Question 13

Which diagnostic method is most sensitive for detecting low levels of viral genetic material in a clinical sample?

Accepted Answer

Polymerase chain reaction (PCR)

Question 14

Which of the following is a limitation of enzyme-linked immunosorbent assays (ELISA) for viral detection?

Accepted Answer

They require the antigen to be well-characterized and may miss viruses that have undergone antigenic shift.

Question 15

Which of the following best describes antigenic drift in influenza viruses?

Accepted Answer

Minor mutations in the HA and NA spike proteins over time

Question 16

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 17

Which of the following is a unique feature of retroviruses compared to other RNA viruses?

Accepted Answer

They use reverse transcriptase to convert their RNA genome into DNA.

Question 18

A virus is described as having icosahedral symmetry, a segmented RNA genome, and an envelope. Which family is it most likely to belong to?

Accepted Answer

Orthomyxoviridae

Question 19

Which of the following best explains why antiviral drugs are more difficult to develop than antibacterial drugs?

Accepted Answer

Viruses use host cell machinery for replication, so there are fewer unique viral targets.

Question 20

Which of the following is a real-world example of a zoonotic virus?

Accepted Answer

Ebola virus

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

Study Guide - Practice Questions