Question 1

Which of the following statements best describes why viruses are considered obligate intracellular parasites?

Accepted Answer

They require living host cells to reproduce because they lack ribosomes and ATP-generating mechanisms.

Question 2

A virus with a helical capsid and an envelope is most likely to be released from a host cell by which process?

Accepted Answer

Budding from the host cell membrane

Question 3

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

Accepted Answer

The spectrum of host cells a virus can infect, determined by specific attachment sites and cellular factors

Question 4

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

Accepted Answer

Reverse transcriptase (RNA-dependent DNA polymerase)

Question 5

A patient is diagnosed with a persistent viral infection that may lead to cancer. Which of the following viruses is most likely involved?

Accepted Answer

Human papillomavirus (HPV)

Question 6

Which of the following best describes the genome of the influenza virus?

Accepted Answer

Single-stranded antisense RNA (ssRNA-)

Question 7

During the lytic cycle of a bacteriophage, what is the correct order of events?

Accepted Answer

Attachment, penetration, biosynthesis, maturation, release

Question 8

Which of the following is a major difference between the multiplication of animal viruses and bacteriophages?

Accepted Answer

Animal viruses require uncoating to release their genome, while bacteriophages inject their genome directly.

Question 9

A virus with a double-stranded RNA genome must carry which enzyme for successful replication in a host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 10

Which of the following best explains why antibiotics are ineffective against viruses?

Accepted Answer

Viruses lack the metabolic pathways targeted by antibiotics.

Question 11

A scientist is studying a virus that causes gastroenteritis and has a nonenveloped, icosahedral structure. Which virus is most likely being studied?

Accepted Answer

Norwalk virus

Question 12

Which of the following best describes the function of viral spikes?

Accepted Answer

They are used for attachment to host cell receptors.

Question 13

A virus with a single-stranded RNA genome of negative polarity must first synthesize which molecule before translation can occur?

Accepted Answer

Single-stranded RNA of positive polarity

Question 14

Which of the following is a characteristic of prions?

Accepted Answer

They are proteinaceous infectious particles that cause spongiform encephalopathies.

Question 15

Which of the following best describes the process of lysogeny in bacteriophages?

Accepted Answer

The phage DNA integrates into the host genome and can confer new properties to the host.

Question 16

A virus is classified as a member of the family Herpesviridae. According to the Baltimore classification, what is the nature of its genome?

Accepted Answer

Double-stranded DNA

Question 17

Which of the following is a real-world example of lysogenic conversion resulting in increased pathogenicity?

Accepted Answer

The production of diphtheria toxin by Corynebacterium diphtheriae after infection by a bacteriophage

Question 18

Which of the following best explains why a ssRNA(-) virus must carry its own RNA-dependent RNA polymerase?

Accepted Answer

Host cells lack the enzyme to convert ssRNA(-) to ssRNA(+).

Question 19

Which of the following is a correct statement about the Baltimore classification system for viruses?

Accepted Answer

It classifies viruses based on their nucleic acid type and how mRNA is produced.

Viruses: Structure, Classification, and Replication

Study Guide - Practice Questions