Question 1

Which of the following best describes the genetic material found in viruses?

Accepted Answer

Viruses may contain either DNA or RNA, which can be single- or double-stranded, linear or circular.

Question 2

Which of the following statements about the viral envelope is correct?

Accepted Answer

The viral envelope is acquired from the host cell during viral replication or release and is composed of a phospholipid bilayer and proteins.

Question 3

Which of the following best explains why most viruses are host-specific?

Accepted Answer

Viral surface proteins have a specific affinity for complementary proteins on the host cell surface.

Question 4

Which of the following is a unique feature of prions compared to viruses and viroids?

Accepted Answer

Prions are infectious proteins that lack nucleic acids.

Question 5

During the lytic replication cycle of a bacteriophage, what is the primary outcome for the host cell?

Accepted Answer

The host cell undergoes lysis and dies, releasing new virions.

Question 6

Which of the following best describes the process of viral uncoating in animal viruses?

Accepted Answer

The removal of the capsid, releasing the viral nucleic acid into the host cell.

Question 7

Which of the following is a correct statement about the replication of retroviruses?

Accepted Answer

Retroviruses use reverse transcriptase to synthesize DNA from their RNA genome.

Question 8

Which of the following is a major difference between the replication of DNA and RNA animal viruses?

Accepted Answer

DNA viruses often replicate in the nucleus, while RNA viruses usually replicate in the cytoplasm.

Question 9

Which of the following best describes lysogenic conversion?

Accepted Answer

It occurs when a prophage alters the phenotype of a bacterium, sometimes giving it new properties such as toxin production.

Question 10

Which of the following is a correct statement about viroids?

Accepted Answer

Viroids are small, circular pieces of single-stranded RNA that are infectious in plants and lack a capsid.

Question 11

Which of the following is the best method for estimating the number of bacteriophages in a sample?

Accepted Answer

Plaque assay, which counts the number of clear zones (plaques) formed on a bacterial lawn.

Question 12

Which of the following statements about the role of viruses in cancer is correct?

Accepted Answer

Viruses can contribute to cancer by carrying oncogenes, promoting host oncogenes, or interfering with tumor repression.

Question 13

Which of the following is true regarding the destruction of prions?

Accepted Answer

Prions are destroyed by incineration or autoclaving in concentrated sodium hydroxide.

Question 14

Which of the following best describes a virion?

Accepted Answer

A complete virus particle in the extracellular state, consisting of a nucleic acid and a protein capsid, and sometimes an envelope.

Question 15

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

Accepted Answer

Binary fission

Question 16

Which of the following statements about enveloped viruses is correct?

Accepted Answer

Enveloped viruses are generally more fragile than naked viruses because their envelopes are sensitive to desiccation, heat, and detergents.

Question 17

Which of the following is a correct statement about the synthesis of negative-sense single-stranded RNA (−ssRNA) viruses?

Accepted Answer

Negative-sense RNA viruses must first synthesize a complementary positive-sense RNA strand to serve as mRNA.

Question 18

Which of the following is a property shared by all viruses but not by prions or viroids?

Accepted Answer

Possession of a protein capsid.

Question 19

A scientist is culturing a newly discovered virus. Which of the following would NOT be an appropriate method for culturing this virus?

Accepted Answer

Growing the virus in a nutrient broth without host cells.

Question 20

Which of the following best explains why viruses are considered acellular?

Accepted Answer

Viruses lack cytoplasmic membrane, cytosol, and functional organelles.

Characterizing and Classifying Viruses, Viroids, and Prions: Microbiology Study Notes

Study Guide - Practice Questions