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 RNA without a protein coat. Which type of agent is this most likely to be?

Accepted Answer

Viroid

Question 3

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

Accepted Answer

It provides protection for the viral nucleic acid and aids in attachment to host cells.

Question 4

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

Accepted Answer

Attachment, Entry, Synthesis, Assembly, Release

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 inject their genome.

Question 6

A patient is diagnosed with a persistent viral infection. Which of the following best explains how enveloped viruses can cause persistent infections?

Accepted Answer

They are released from the host cell by budding, allowing the cell to survive and continue producing virus.

Question 7

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

Accepted Answer

It may be DNA or RNA, single-stranded or double-stranded, but never both DNA and RNA.

Question 8

A prion disease is characterized by which of the following molecular changes?

Accepted Answer

Conversion of normal cellular PrP with α-helices into prion PrP with β-sheets.

Question 9

Which of the following is the primary method for classifying viruses?

Accepted Answer

Type of nucleic acid, presence of envelope, shape, and size

Question 10

A laboratory is preparing a vaccine using a virus that must be grown in a medium free of contaminating microbes and rich in nutrients. Which of the following is the most appropriate method for culturing this virus?

Accepted Answer

Inoculation into embryonated chicken eggs

Question 11

Which of the following best explains why lysogenic and latent viral infections are generally longer lasting than lytic infections?

Accepted Answer

The viral genome is integrated into the host DNA and can remain dormant for extended periods.

Question 12

A plant is found to be infected by a pathogen that lacks a capsid and consists only of a small, circular RNA molecule. Which hypothesis best explains the origin of this pathogen?

Accepted Answer

It may have originated from introns, as suggested by the intron hypothesis for viroids.

Question 13

Which of the following is a correct statement about the synthesis of animal DNA viruses?

Accepted Answer

dsDNA viruses replicate their genome in the nucleus, while viral proteins are made in the cytoplasm.

Question 14

A patient is exposed to a prion-contaminated surgical instrument. Which of the following methods is most effective for destroying prions on the instrument?

Accepted Answer

Incineration or autoclaving in concentrated sodium hydroxide

Question 15

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

Accepted Answer

The virus acquires its envelope from the host cell membrane as it exits the cell.

Question 16

A researcher is studying a virus with a segmented, negative-sense single-stranded RNA genome. Which enzyme must this virus carry or encode to replicate in a host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 17

Which of the following is a plausible reason why scientists initially resisted the idea of an infectious protein?

Accepted Answer

Proteins were not thought to be capable of self-replication or transmitting genetic information.

Question 18

A virus infects only hepatocytes in humans but not other cell types. This specificity is most likely due to:

Accepted Answer

The presence of specific receptors on hepatocytes that the virus recognizes.

Question 19

Which of the following best describes the difference between a virion and a provirus?

Accepted Answer

A virion is the extracellular, infectious form of a virus, while a provirus is the viral genome integrated into the host DNA.

Question 20

A bacteriophage is observed to carry genes that alter the phenotype of its bacterial host, such as toxin production. This phenomenon is best described as:

Accepted Answer

Lysogenic conversion

chapter 13

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