Question 1

Which of the following best describes a virus?

Accepted Answer

An acellular genetic element that cannot replicate independently of a living host cell

Question 2

Which of the following is NOT a component of all viruses?

Accepted Answer

Envelope

Question 3

What is the primary function of the viral capsid?

Accepted Answer

To protect the viral genome and facilitate its transfer between host cells

Question 4

Which of the following statements about viral envelopes is TRUE?

Accepted Answer

Animal virus envelopes usually arise from host cell plasma or nuclear membranes

Question 5

Which enzyme is carried by retroviruses and is essential for their replication?

Accepted Answer

Reverse transcriptase

Question 6

According to the Baltimore classification, which class of viruses contains double-stranded RNA genomes?

Accepted Answer

Class III

Question 7

During the viral life cycle, what is the main difference between the lytic and lysogenic cycles in bacteriophages?

Accepted Answer

The lytic cycle leads to host cell lysis and release of new virions, while the lysogenic cycle involves integration of the viral genome into the host chromosome

Question 8

Which of the following best describes a viroid?

Accepted Answer

A small, circular, single-stranded RNA molecule that lacks a protein coat

Question 9

What is the role of the cI protein in the lambda (λ) bacteriophage life cycle?

Accepted Answer

It represses lytic events and maintains lysogeny

Question 10

Which of the following is a common method for quantifying viruses in a laboratory setting?

Accepted Answer

Plaque assay

Question 11

A patient is diagnosed with Creutzfeldt-Jakob disease (CJD). Which type of infectious agent is responsible for this disease?

Accepted Answer

Prion

Question 12

Which of the following statements about prions is FALSE?

Accepted Answer

Prions contain both protein and nucleic acid

Question 13

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

Accepted Answer

They require a host cell's machinery to replicate

Question 14

Which of the following is a function of viral envelope proteins?

Accepted Answer

Attachment to host cells and immune system evasion

Question 15

A virus with a (+)ssRNA genome must encode which enzyme for replication in a host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 16

Which of the following statements about the viral growth curve is TRUE?

Accepted Answer

The latent period includes both the eclipse and maturation phases

Question 17

Which of the following is a defense mechanism used by prokaryotes against viral infection?

Accepted Answer

Restriction modification systems

Question 18

Which of the following best describes a satellite virus?

Accepted Answer

A virus that requires a helper virus for replication

Question 19

Which of the following is a real-world example of a virus acting as a biocontrol agent?

Accepted Answer

Pseudomonas plecoglossicida phage used in fish treatment

Question 20

Which of the following is TRUE regarding the difference between naked and enveloped viruses?

Accepted Answer

Enveloped viruses acquire their envelope from the host cell membrane

Viruses and Other Acellular Infectious Agents: Structure, Classification, and Life Cycle

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