Question 1

Which of the following best describes the main difference between the lytic and lysogenic cycles of a bacteriophage?

Accepted Answer

The lytic cycle results in the destruction of the host cell, while the lysogenic cycle allows the phage genome to persist in the host without killing it.

Question 2

During the lysogenic cycle, what is the term for the phage DNA that is integrated into the bacterial chromosome?

Accepted Answer

Prophage

Question 3

Which of the following is an evolutionary advantage of the lysogenic cycle for temperate bacteriophages?

Accepted Answer

It enables the phage to persist in the host population during unfavorable conditions.

Question 4

Which step is unique to the replication of enveloped animal viruses compared to non-enveloped animal viruses?

Accepted Answer

Entry by membrane fusion with the host cell

Question 5

A virus that acquires its envelope as it exits the host cell is most likely to:

Accepted Answer

Budge from the host cell membrane, taking part of the membrane as its envelope

Question 6

Which enzyme is essential for the biosynthesis of retroviruses, and what is its function?

Accepted Answer

Reverse transcriptase; it synthesizes DNA from an RNA template: $$	ext{RNA} ightarrow 	ext{DNA}$$

Question 7

What is a provirus, and which family of viruses is known to form proviruses?

Accepted Answer

A provirus is viral DNA integrated into a eukaryotic host genome; Retroviridae form proviruses.

Question 8

Which of the following statements correctly distinguishes a prophage from a provirus?

Accepted Answer

A prophage is integrated viral DNA in a bacterial genome, while a provirus is integrated viral DNA in a eukaryotic genome.

Question 9

Which of the following viruses is associated with the development of human warts and some cancers?

Accepted Answer

Papovaviridae

Question 10

A patient presents with a persistent viral infection that produces low levels of virus over many years, eventually leading to liver cancer. Which virus is most likely responsible?

Accepted Answer

Hepatitis B virus

Question 11

Which of the following is an example of a latent viral infection?

Accepted Answer

Herpes simplex virus remaining dormant in nerve cells and reactivating later

Question 12

Which of the following best describes prions?

Accepted Answer

Infectious proteins that cause neurodegenerative diseases

Question 13

Which disease is NOT caused by prions?

Accepted Answer

Poliomyelitis

Question 14

Antigenic shift in influenza viruses can lead to which of the following?

Accepted Answer

A pandemic due to the emergence of a novel virus subtype

Question 15

Which process is responsible for the gradual accumulation of mutations in viral genes, leading to seasonal epidemics?

Accepted Answer

Antigenic drift

Question 16

A diagnostic test for a viral infection has a sensitivity of $$95\%$$ and a specificity of $$90\%. $$What does this mean?

Accepted Answer

The test correctly identifies $$95\% of $$true positives and $$90\% of $$true negatives.

Question 17

Which of the following is a potential antiviral drug target that would specifically inhibit the replication of retroviruses?

Accepted Answer

Reverse transcriptase enzyme

Question 18

Which virus family includes the causative agent of the common cold?

Accepted Answer

Picornaviridae

Question 19

A new influenza strain emerges due to the reassortment of gene segments from two different influenza viruses. This is an example of:

Accepted Answer

Antigenic shift

Question 20

Which of the following best describes an epidemic?

Accepted Answer

A sudden increase in the number of cases of a disease above what is normally expected in a specific area

Microbiology Study Guide: Viruses, Replication Cycles, and Related Concepts

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