Question 1

Which of the following statements best describes a key difference between viruses and prokaryotic cells?

Accepted Answer

Viruses lack cellular structure and do not exhibit metabolism, whereas prokaryotic cells are living and metabolically active.

Question 2

A virus particle contains which of the following components?

Accepted Answer

Capsid, genetic material, and sometimes an envelope

Question 3

Antigenic shift in influenza viruses is best described as:

Accepted Answer

A sudden change due to reassortment of genome segments between different viral strains

Question 4

Which factor most directly determines a virus's host range?

Accepted Answer

The compatibility between viral surface proteins and host cell receptors

Question 5

During bacteriophage lytic replication, which event occurs first after the phage attaches to the bacterial cell?

Accepted Answer

Injection of phage genetic material into the host

Question 6

Which of the following best describes the lysogenic cycle of a bacteriophage?

Accepted Answer

The phage DNA integrates into the host genome and is replicated along with it

Question 7

A patient is diagnosed with a latent viral infection. Which of the following best describes this type of infection?

Accepted Answer

The virus remains dormant in host cells and can reactivate later.

Question 8

Selective pressure from antiviral drugs can lead to viral evolution by:

Accepted Answer

Promoting mutations that confer drug resistance

Question 9

Which process allows bacteria to acquire new genetic material from bacteriophages, potentially increasing pathogenicity?

Accepted Answer

Transduction via phage conversion

Question 10

In a laboratory plaque assay, what does the appearance of clear zones (plaques) on a bacterial lawn indicate?

Accepted Answer

Areas where viruses have lysed bacterial cells

Question 11

Which of the following antiviral drugs inhibits viral DNA synthesis by acting as a nucleoside analog?

Accepted Answer

Acyclovir

Question 12

A virus with a segmented RNA genome is capable of which evolutionary process, leading to new viral strains?

Accepted Answer

Antigenic shift

Question 13

Which equation best represents the calculation of viral titer in a plaque assay?

Accepted Answer

$Viral\ titer = \frac{Number\ of\ plaques}{Dilution\ factor 	imes Volume\ plated}$

Question 14

Which of the following is NOT a function of the viral envelope?

Accepted Answer

Providing energy for viral replication

Question 15

Which scenario best illustrates tropism in viral infections?

Accepted Answer

A virus infects only liver cells due to specific receptor binding

Question 16

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

Accepted Answer

They cannot replicate without a host cell and lack independent metabolism

Question 17

Which step in the lytic cycle directly leads to the release of new viral particles?

Accepted Answer

Lysis of the host cell

Question 18

A scientist observes that a bacteriophage can infect only E. coli and not Salmonella. This is most likely due to:

Accepted Answer

Presence of specific receptors on E. coli recognized by the phage

Question 19

Which of the following is a consequence of antigenic drift in influenza viruses?

Accepted Answer

Gradual changes in viral surface proteins leading to seasonal epidemics

Question 20

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

Accepted Answer

They allow the virus to attach to specific host cell receptors

Study Guide: Viruses and Bacteriophages in Microbiology

Study Guide - Practice Questions