Question 1

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

Accepted Answer

They lack a cytoplasmic membrane, cytosol, and organelles.

Question 2

A scientist discovers a new infectious agent that consists of a small, circular piece of single-stranded RNA without a protein coat. Which type of agent is this most likely to be?

Accepted Answer

A viroid

Question 3

Which of the following best describes the role of the viral envelope?

Accepted Answer

It is acquired from the host cell membrane and contains glycoproteins that aid in host recognition.

Question 4

During the lysogenic cycle of a bacteriophage, what is the term for the viral DNA that is integrated into the host cell’s chromosome?

Accepted Answer

Prophage

Question 5

Which of the following is a key difference between the replication of animal viruses and bacteriophages?

Accepted Answer

Animal viruses may enter host cells by membrane fusion or endocytosis, while bacteriophages typically inject their genome.

Question 6

Which of the following best explains why enveloped viruses are generally more sensitive to environmental conditions than naked viruses?

Accepted Answer

Their phospholipid envelope is susceptible to desiccation, detergents, and solvents.

Question 7

A patient is diagnosed with a disease caused by a prion. Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause normal proteins to misfold into a disease-causing form.

Question 8

Which of the following is a correct statement about the synthesis of RNA viruses in animal cells?

Accepted Answer

Positive-sense (+) RNA viruses can serve directly as mRNA for protein synthesis.

Question 9

Which of the following best describes lysogenic conversion?

Accepted Answer

It is when a prophage alters the phenotype of its bacterial host, sometimes resulting in new traits such as toxin production.

Question 10

Which of the following is a real-world example of a disease caused by a viroid?

Accepted Answer

Potato spindle tuber disease

Question 11

A virus with a double-stranded DNA genome and an envelope is most likely to replicate its genome in which part of the host cell?

Accepted Answer

Nucleus

Question 12

Which of the following best explains why viruses are not classified as living organisms?

Accepted Answer

They cannot carry out metabolic processes independently.

Question 13

Which of the following is a mechanism by which animal viruses can enter host cells?

Accepted Answer

Membrane fusion

Question 14

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

Accepted Answer

Some viruses carry oncogenes or activate host oncogenes, leading to uncontrolled cell division.

Question 15

Which of the following is the best method for destroying prions on contaminated medical equipment?

Accepted Answer

Incineration or autoclaving in concentrated sodium hydroxide

Question 16

A virus is found to have a helical capsid and a single-stranded negative-sense RNA genome. Which family is it most likely to belong to?

Accepted Answer

Rhabdoviridae

Question 17

Which of the following best describes the process of uncoating in animal virus replication?

Accepted Answer

The capsid is removed to release the viral genome inside the host cell.

Question 18

Which of the following is a distinguishing feature of retroviruses?

Accepted Answer

They use reverse transcriptase to synthesize DNA from an RNA template.

Question 19

Which of the following is a plausible reason why viruses are difficult to classify taxonomically compared to cellular organisms?

Accepted Answer

Their evolutionary relationships are not well understood and they lack many features used in cellular classification.

Question 20

Which of the following best describes the outcome of the lytic replication cycle in bacteriophages?

Accepted Answer

The host cell is lysed, releasing new virions.

Ch. 13 Viruses, Viroids, and Prions: Structure, Classification, and Replication

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