Question 1

Which of the following best explains why viruses are considered obligate intracellular parasites?

Accepted Answer

They require host cell machinery for replication because they lack ribosomes and energy production systems.

Question 2

A scientist discovers a new infectious agent composed solely of a short strand of RNA with no protein coat. Which of the following best describes this agent?

Accepted Answer

Viroid

Question 3

Which structural component is responsible for the attachment of enveloped viruses to host cells?

Accepted Answer

Spikes

Question 4

A patient is diagnosed with a persistent viral infection. Which of the following best characterizes this type of infection?

Accepted Answer

The infection develops slowly over time and is often fatal.

Question 5

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that can cause neurodegenerative diseases.

Question 6

A virus is found to have a helical capsid and an envelope. Which of the following best describes its structure?

Accepted Answer

The virus has a helical protein shell surrounded by a lipid envelope.

Question 7

Which of the following best distinguishes the lytic cycle from the lysogenic cycle in bacteriophages?

Accepted Answer

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

Question 8

A laboratory is attempting to culture a newly discovered virus. Which of the following methods would NOT be suitable for viral growth?

Accepted Answer

Culturing in nutrient agar plates without host cells

Question 9

Which of the following is a key feature of oncogenic viruses?

Accepted Answer

They integrate their genetic material into the host cell's chromosomes, potentially activating oncogenes.

Question 10

A virologist is using PCR to detect a viral infection. What is the main advantage of this method?

Accepted Answer

It amplifies specific viral nucleic acids, allowing for sensitive and specific detection.

Question 11

Which of the following best describes a virion?

Accepted Answer

A fully developed infectious viral particle outside a host cell

Question 12

A virus infects only liver cells in humans. This specificity is most likely due to:

Accepted Answer

The presence of specific receptors on liver cells that interact with viral spikes.

Question 13

Which of the following is NOT a characteristic of viruses?

Accepted Answer

They contain both DNA and RNA in the same particle.

Question 14

A patient develops a brain disorder after exposure to an infectious agent that contains no nucleic acids. Which agent is most likely responsible?

Accepted Answer

Prion

Question 15

Which of the following best explains why viroids are unique among infectious agents?

Accepted Answer

They are composed solely of naked RNA without a protein coat.

Question 16

A virus is found to cause cancer by activating host cell oncogenes. Which of the following processes is most likely involved?

Accepted Answer

Integration of viral DNA into the host genome

Question 17

Which of the following equations best represents the exponential increase in viral particles during the lytic cycle, assuming each infected cell releases $$n$$ new virions and $$k$$ cycles occur?

Accepted Answer

$$N = n^k$$

Question 18

A researcher observes that a viral infection remains undetectable for years before symptoms appear. This infection is best described as:

Accepted Answer

Latent

Question 19

Which of the following is a common method for detecting viral infections in the laboratory?

Accepted Answer

Observation of cytopathic effects in cell cultures

Question 20

A virus with a polyhedral capsid and no envelope is most likely to be:

Accepted Answer

Resistant to drying and detergents

Viruses, Viroids, and Prions: Structure, Multiplication, and Pathogenicity

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