Question 1

Which of the following best describes the structure labeled as the 'capsid' in a virus?

Accepted Answer

A protein coat that protects the viral nucleic acid from environmental damage.

Question 2

Which of the following statements about enveloped viruses is correct?

Accepted Answer

They obtain their envelope from the host cell membrane during viral assembly.

Question 3

A virus with a helical capsid structure would most likely appear:

Accepted Answer

Cylindrical, with capsid proteins arranged in a spiral.

Question 4

During a plaque assay, what does each plaque on a bacterial lawn represent?

Accepted Answer

A single phage particle that initiated infection.

Question 5

Which step in the animal virus infection cycle involves the release of viral DNA from its protein coat into the host cell cytoplasm?

Accepted Answer

Uncoating

Question 6

Which of the following is NOT a step in the lytic phage reproductive cycle?

Accepted Answer

Packaging of the phage’s cytoplasm

Question 7

What is the main difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in immediate lysis of the host cell, while the lysogenic cycle involves integration of phage DNA into the host genome.

Question 8

A bacterial cell carrying a prophage in its chromosome is called a:

Accepted Answer

Lysogen

Question 9

Which of the following best explains why enveloped viruses are more susceptible to soaps and disinfectants?

Accepted Answer

Soaps disrupt the viral envelope, preventing the virus from attaching to host cells.

Question 10

Which method of entry is unique to enveloped viruses and why?

Accepted Answer

Entry via membrane fusion, because enveloped viruses have an outer membrane that fuses with the host cell membrane.

Question 11

Which of the following is a requirement for the replication of (-) ssRNA viruses?

Accepted Answer

The virus must bring its own replicase enzyme into the host cell.

Question 12

Which of the following is NOT found in any virus?

Accepted Answer

Ribosomes

Question 13

A positive-sense single-stranded RNA ((+) ssRNA) virus can:

Accepted Answer

Be directly translated by host ribosomes to produce viral proteins.

Question 14

Which of the following best describes a persistent viral infection?

Accepted Answer

The virus remains present in the host for months, years, or the host's lifetime.

Question 15

Which of the following is a characteristic of latent viral infections?

Accepted Answer

The viral genome remains silent in the host cell and can reactivate later.

Question 16

Which of the following would allow a scientist to conclude that a specimen is NOT a virus?

Accepted Answer

The specimen contains both DNA and RNA.

Question 17

Viroids are best described as:

Accepted Answer

Small fragments of naked ssRNA that infect plant cells.

Question 18

Which of the following is true of prions?

Accepted Answer

They are a rogue form of protein, PrP.

Question 19

Why are prion diseases in meat a significant concern for public health?

Accepted Answer

Prions cannot be destroyed by cooking, irradiation, or standard sterilization methods.

Question 20

Which of the following statements about the SARS-CoV-2 virus (Covid-19) is correct?

Accepted Answer

It is an enveloped, icosahedral, (+) ssRNA virus that can be directly translated by host ribosomes.

Viruses, Viroids, and Prions: Structure, Replication, and Infection

Study Guide - Practice Questions