Question 1

Which of the following best describes the main difference between the lytic and lysogenic cycles of a bacteriophage?

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle allows the phage genome to integrate into the host genome and replicate with it.

Question 2

A scientist is developing a phage therapy to treat a bacterial infection. Which type of phage would be most effective and why?

Accepted Answer

A lytic phage, because it will destroy the bacterial cells and quickly reduce the infection.

Question 3

Which step in the lytic replication cycle of a bacteriophage involves the synthesis of viral nucleic acids and proteins using host cell machinery?

Accepted Answer

Synthesis

Question 4

What is the primary reason why lytic phages do not increase the virulence of bacterial pathogens by carrying toxin genes?

Accepted Answer

Lytic phages immediately destroy the bacterial cell’s genome, preventing expression of any new genes.

Question 5

Which of the following is NOT a method by which animal viruses can enter host cells?

Accepted Answer

Budding

Question 6

Why is uncoating an essential step in the animal virus life cycle?

Accepted Answer

The viral genome must be released from the capsid to be accessible for replication and transcription.

Question 7

Which unique viral enzyme must retroviruses like HIV package into their virions, and why?

Accepted Answer

Reverse transcriptase, because host cells do not have this enzyme to convert viral RNA into DNA.

Question 8

Which process describes how enveloped animal viruses acquire their envelope during release from the host cell?

Accepted Answer

Budding

Question 9

A virus uses an RNA-dependent RNA polymerase to synthesize mRNA for protein production. What type of genome must this virus have?

Accepted Answer

Either a single-stranded RNA (ssRNA) or double-stranded RNA (dsRNA) genome

Question 10

Which entry method for animal viruses most closely resembles the process of viral budding, but in reverse?

Accepted Answer

Membrane fusion

Question 11

Which of the following best describes a viroid?

Accepted Answer

A small, circular, single-stranded RNA molecule that lacks a protein coat and only infects plants.

Question 12

How do prions cause disease in animals?

Accepted Answer

They induce misfolding of normal proteins, leading to protein aggregates that kill cells.

Question 13

Which of the following methods is recommended by the CDC for destroying prions on contaminated surgical instruments?

Accepted Answer

Immersion in 1N NaOH followed by autoclaving at high temperature.

Question 14

Which of the following is a key difference between viruses and prions?

Accepted Answer

Viruses contain nucleic acids, while prions are composed only of protein.

Question 15

A patient is diagnosed with Creutzfeldt-Jakob disease. What is the most likely cause of this disease?

Accepted Answer

Infection with a prion protein that induces misfolding of normal brain proteins.

Question 16

Which of the following best explains why viroids only infect plants and not animals?

Accepted Answer

Viroids enter plant cells through wounds and do not require protein receptors, which are necessary for animal cell infection.

Question 17

Which of the following is a real-world application of plaque assays in virology?

Accepted Answer

Quantifying the number of infectious viral particles in a sample.

Question 18

Which of the following statements about viral budding is correct?

Accepted Answer

Budding allows enveloped viruses to exit the host cell without lysing it.

Question 19

Which of the following best describes the role of induction in the lysogenic cycle of a bacteriophage?

Accepted Answer

Induction triggers the prophage to exit the host genome and enter the lytic cycle.

Acellular Infectious Agents: Viruses, Viroids, and Prions – Structure, Life Cycles, and Pathogenesis

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