Question 1

Which of the following best describes the structure of a typical icosahedral virus?

Accepted Answer

A spherical capsid composed of 20 triangular faces and 12 vertices

Question 2

What is the primary function of the viral capsid?

Accepted Answer

To protect the viral nucleic acid from environmental damage

Question 3

Which types of nucleic acids can be found in viruses?

Accepted Answer

Both RNA and DNA, which may be single- or double-stranded

Question 4

A virus is classified as enveloped. What structural feature does it possess?

Accepted Answer

A lipid membrane surrounding its capsid

Question 5

During the lytic cycle of a bacteriophage, which step immediately follows the synthesis of viral proteins and genomes?

Accepted Answer

Assembly of phage components

Question 6

Which of the following best explains why enveloped viruses are more sensitive to heat than non-enveloped viruses?

Accepted Answer

Heat denatures the lipid envelope, disrupting viral infectivity

Question 7

In the lysogenic cycle of bacteriophages, what is the term for the integrated phage DNA within the host chromosome?

Accepted Answer

Prophage

Question 8

Which step is unique to animal virus replication compared to bacteriophage replication?

Accepted Answer

Uncoating of the viral capsid inside the host cell

Question 9

A patient is infected with a non-enveloped virus. Which environmental condition is this virus most likely to withstand compared to an enveloped virus?

Accepted Answer

Freeze-thaw cycles

Question 10

Which of the following is TRUE regarding prions?

Accepted Answer

They are infectious agents composed only of misfolded proteins

Question 11

Which process allows a lysogenic bacteriophage to switch to the lytic cycle?

Accepted Answer

Excision of prophage DNA from the host chromosome

Question 12

Viruses are implicated in approximately what percentage of human cancers?

Accepted Answer

20-25\%

Question 13

Which of the following best describes the role of viral oncogenes in cancer development?

Accepted Answer

They promote uncontrolled cell division by activating host oncogenes

Question 14

A virus with a helical capsid is most likely to have which of the following shapes?

Accepted Answer

Rod-like

Question 15

Which of the following steps is NOT part of the lytic cycle of bacteriophages?

Accepted Answer

Integration of phage DNA into the host chromosome

Question 16

Which equation best represents the exponential increase in viral particles during the lytic cycle, assuming each infected cell releases $$N$$ new virions and $$t$$ cycles occur?

Accepted Answer

$$V = N^t$$

Question 17

A scientist is studying a virus that lacks an envelope and survives in harsh environments. Which structural feature most likely contributes to its stability?

Accepted Answer

A protein capsid without a lipid membrane

Question 18

Which of the following is a key difference between prion diseases and viral infections?

Accepted Answer

Prion diseases are caused by misfolded proteins, not nucleic acids

Question 19

Which step in animal virus replication involves the fusion of the viral envelope with the host cell membrane?

Accepted Answer

Entry

Question 20

A virus is found to cause transmissible spongiform encephalopathies. What is the most likely infectious agent?

Accepted Answer

Prion

Fundamentals of Viruses and Prions: Structure, Replication, and Pathogenicity

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