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 contains only a circular piece of single-stranded RNA and lacks 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 facilitates attachment to host cells.

Question 4

During the lytic replication cycle of a bacteriophage, what is the correct order of the five 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 typically inject their genome.

Question 6

A patient is diagnosed with a cancer that is linked to a viral infection. Which of the following mechanisms best explains how viruses can contribute to cancer development?

Accepted Answer

Viruses can carry oncogenes or activate host oncogenes, leading to uncontrolled cell division.

Question 7

Which of the following best explains why enveloped viruses are generally more fragile than naked viruses?

Accepted Answer

Their phospholipid bilayer envelope is sensitive to desiccation, heat, and detergents.

Question 8

A virologist is culturing a virus that only infects human T cells. Early in AIDS research, this was difficult. Which technological advancement most likely enabled scientists to culture HIV in the lab?

Accepted Answer

Development of continuous human T cell lines that can be maintained in vitro.

Question 9

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause normal cellular PrP to refold into a disease-causing form.

Question 10

A virus with a genome composed of $-ssRNA$ must first do which of the following upon entering a host cell?

Accepted Answer

Synthesize a complementary $+ssRNA$ to serve as mRNA for protein synthesis.

Question 11

Which of the following best describes the process of lysogenic conversion in bacteria?

Accepted Answer

A bacterium acquires new traits due to genes carried by a prophage.

Question 12

Why are DNA viruses more likely than RNA viruses to cause neoplasias (tumors) in humans?

Accepted Answer

DNA viruses can integrate into the host genome, potentially disrupting genes that regulate cell division.

Question 13

Which of the following laboratory methods is most commonly used to estimate the number of bacteriophages in a sample?

Accepted Answer

Counting plaques formed on a bacterial lawn.

Question 14

A researcher is studying a virus with a segmented, double-stranded RNA genome. Which of the following statements is true regarding its replication?

Accepted Answer

The virus must synthesize mRNA from each RNA segment for protein production.

Question 15

Which of the following best explains why normal sterilization procedures are ineffective against prions?

Accepted Answer

Prions are highly resistant to heat and chemicals that denature nucleic acids.

Question 16

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

Accepted Answer

Creutzfeldt-Jakob disease

Question 17

A virus is found to infect both plants and animals. Which term best describes this virus?

Accepted Answer

Generalist

Question 18

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

Accepted Answer

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

Question 19

Which of the following is a characteristic unique to retroviruses among animal viruses?

Accepted Answer

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

Question 20

A patient is infected with a virus that remains dormant in host cells for years before becoming active. What is this phenomenon called?

Accepted Answer

Latency

Characterization and Classification of Viruses, Viroids, and Prions

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