Question 1

Which of the following statements best distinguishes between a virus and a prion?

Accepted Answer

A virus contains a nucleic acid genome surrounded by a protein coat, while a prion is an infectious protein without nucleic acid.

Question 2

Which of the following best describes the structure labeled as 'helical capsid' in an enveloped virus?

Accepted Answer

A rod-shaped arrangement of capsomere proteins surrounding the viral genome.

Question 3

Why is the type of viral genome (DNA or RNA, single- or double-stranded) important for the replication mechanism of a virus?

Accepted Answer

The genome type determines which enzymes and replication strategies the virus must use inside the host cell.

Question 4

A bacteriophage is missing its tail fibers due to a mutation. Which step of the viral life cycle will be most directly affected?

Accepted Answer

Attachment to the host cell.

Question 5

Which of the following is NOT a reason why the entire virion does not enter a bacterial cell during phage infection?

Accepted Answer

Virions are smaller than the cells they infect.

Question 6

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

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

Question 7

A virus with a single-stranded, positive-sense RNA genome is classified as which Baltimore class?

Accepted Answer

Class IV

Question 8

Which of the following is a unique property of viruses compared to cells?

Accepted Answer

Viruses are obligate intracellular parasites that replicate using the enzymes and organelles of a host cell.

Question 9

During the release step of the viral life cycle, which process is used by enveloped viruses to exit the host cell?

Accepted Answer

Budding through the host cell membrane, acquiring a lipid envelope.

Question 10

A patient is infected with a virus that has a double-stranded DNA genome and an icosahedral capsid. Which of the following viruses is most likely responsible?

Accepted Answer

Adenovirus

Question 11

Which of the following best explains why viruses are not considered living organisms?

Accepted Answer

They do not metabolize or grow on their own and require a host cell for replication.

Question 12

Which of the following steps in the viral life cycle involves the use of host cell ribosomes to produce viral proteins?

Accepted Answer

Synthesis

Question 13

A temperate phage has integrated its genome into the host bacterial chromosome. What is this integrated phage genome called?

Accepted Answer

Prophage

Question 14

Which of the following is a correct sequence of events in the lytic replication cycle of a bacteriophage?

Accepted Answer

Attachment → Entry → Synthesis → Assembly → Release

Question 15

A virus is observed to have a polyhedral capsid and no envelope. Which of the following best describes this virus?

Accepted Answer

It is a naked virus with an icosahedral capsid.

Question 16

Which of the following best explains why bacteriophages are being considered as treatments for bacterial infections?

Accepted Answer

They specifically infect and lyse bacterial cells, reducing bacterial populations.

Question 17

Which of the following is a property shared by all acellular infectious agents?

Accepted Answer

They require a living host cell for replication.

Question 18

A virus with a genome that is complementary to mRNA is classified as which type?

Accepted Answer

Minus-sense single-stranded RNA (−ssRNA)

Question 19

Which of the following best describes the function of viral glycoproteins found in the envelope of some viruses?

Accepted Answer

They mediate attachment to specific host cell receptors.

Question 20

A scientist observes a virus that is released from the host cell by budding. Which of the following statements is most likely true about this virus?

Accepted Answer

It acquires a lipid envelope from the host cell membrane during release.

Acellular Infectious Agents: Viruses, Prions, and Viroids – Structure, Classification, and Life Cycles

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