Question 1

Which of the following best describes a virion?

Accepted Answer

A complete virus particle consisting of nucleic acid surrounded by a protein coat and possibly external layers

Question 2

What is the main difference between a naked virus and an enveloped virus?

Accepted Answer

Naked viruses lack a lipid bilayer envelope, while enveloped viruses have an outer lipid bilayer derived from the host cell membrane

Question 3

A virus with icosahedral capsid symmetry in the head region and helical symmetry in the tail is said to have what type of symmetry?

Accepted Answer

Binal symmetry

Question 4

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-stranded or double-stranded, linear, circular, or segmented

Question 5

Which enzyme is required for the integration of a temperate phage genome into the host chromosome during lysogeny?

Accepted Answer

Integrase

Question 6

Which of the following best describes a negative-sense single-stranded RNA virus?

Accepted Answer

Its genome is complementary to mRNA and must be converted to positive-sense RNA before translation

Question 7

Which step in the viral replication cycle involves the removal of the capsid to release the viral genome into the host cell?

Accepted Answer

Uncoating

Question 8

Which of the following conditions could induce the lytic cycle in a prophage?

Accepted Answer

Decreased levels of lambda repressor or exposure to UV light

Question 9

A persistent viral infection is characterized by which of the following?

Accepted Answer

The virus is almost always detectable, and clinical symptoms may be mild or absent for long periods

Question 10

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

Accepted Answer

Human papillomavirus (HPV)

Question 11

Which enzyme is unique to retroviruses and is essential for their replication?

Accepted Answer

Reverse transcriptase

Question 12

A virus that infects bacteria is called a:

Accepted Answer

Bacteriophage

Question 13

Which of the following best explains why most bacteriophages do not have an envelope?

Accepted Answer

Bacteriophages are released by lysis, not budding, so they do not acquire a host-derived lipid bilayer

Question 14

Which of the following is a correct sequence of events for the lytic cycle of a bacteriophage?

Accepted Answer

Attachment, penetration, synthesis, assembly, release

Question 15

Which of the following statements about viral envelopes is true?

Accepted Answer

Viral envelopes are usually derived from the host cell membrane and may contain viral-encoded proteins called spikes

Question 16

A positive-sense single-stranded RNA virus can:

Accepted Answer

Use its genome directly as mRNA for translation

Question 17

Which of the following best describes the process of lysogenic conversion?

Accepted Answer

A prophage alters the phenotype of its bacterial host

Question 18

SARS-CoV-2 is classified as which of the following?

Accepted Answer

An enveloped, positive-sense, single-stranded RNA virus with helical capsid symmetry

Question 19

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

Accepted Answer

Herpes simplex virus (HSV) causing cold sores that recur after periods of dormancy

Question 20

Which of the following best explains why retroviruses are unique among RNA viruses?

Accepted Answer

They use reverse transcriptase to synthesize DNA from their RNA genome

Viruses: Structure, Classification, and Replication

Study Guide - Practice Questions