Question 1

Which of the following statements best describes the difference between the extracellular and intracellular states of a virus?

Accepted Answer

In the extracellular state, the virus is called a virion and is surrounded by a capsid; in the intracellular state, the capsid is removed and the virus exists as nucleic acid.

Question 2

Which component is present in all viruses but absent in prions and viroids?

Accepted Answer

Capsid

Question 3

A virus with a helical capsid and an envelope would most likely:

Accepted Answer

Be more sensitive to detergents and solvents than a naked virus

Question 4

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

Accepted Answer

Viral surface proteins have affinity for specific complementary proteins on host cell surfaces

Question 5

During the lytic replication cycle of a bacteriophage, which event occurs immediately after synthesis of viral components?

Accepted Answer

Assembly of new virions

Question 6

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 into the host.

Question 7

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

Accepted Answer

A bacteriophage integrates its genome into the host chromosome, potentially altering the host's phenotype.

Question 8

Which of the following viruses would require reverse transcriptase for replication?

Accepted Answer

Retroviruses

Question 9

A scientist is culturing a virus that cannot grow in standard microbiological media. Which of the following methods would be most appropriate?

Accepted Answer

Inoculation into embryonated chicken eggs

Question 10

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause normal cellular proteins to refold into abnormal shapes.

Question 11

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

Accepted Answer

Their lipid envelope is easily disrupted by detergents and solvents.

Question 12

A patient is diagnosed with a viral cancer. Which of the following mechanisms could explain how the virus contributed to cancer development?

Accepted Answer

The virus inserted its genome near a proto-oncogene, disrupting normal cell cycle regulation.

Question 13

Which of the following is a characteristic of viroids but not viruses?

Accepted Answer

They are small, circular pieces of ssRNA that lack a capsid.

Question 14

Which of the following best describes the role of glycoprotein spikes on enveloped viruses?

Accepted Answer

They mediate attachment to host cell receptors.

Question 15

A virus with a segmented, double-stranded RNA genome would most likely belong to which family?

Accepted Answer

Reoviridae

Question 16

Which of the following is a correct statement about the synthesis of viral mRNA in +ssRNA viruses?

Accepted Answer

The viral genome acts directly as mRNA.

Question 17

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

Accepted Answer

They require host cell machinery to replicate and produce new virions.

Question 18

Which of the following is the most likely outcome if a virus integrates its genome into the host DNA and remains dormant for years?

Accepted Answer

Latency

Question 19

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

Accepted Answer

Plaque assay

Question 20

Which of the following is NOT a standard method for destroying prions?

Accepted Answer

Standard autoclaving at 121°C for 15 minutes

Viruses, Viroids, and Prions: Structure, Classification, and Replication

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