Question 1

Which of the following best describes a virion?

Accepted Answer

The extracellular, infectious form of a virus that contains the viral genome.

Question 2

Which of the following is NOT a possible type of viral genome?

Accepted Answer

Double-stranded protein

Question 3

A virus that can integrate its genome into the host cell’s DNA and remain dormant is called:

Accepted Answer

A temperate virus

Question 4

Which structure is found in enveloped viruses but NOT in naked viruses?

Accepted Answer

Lipid bilayer membrane

Question 5

The one-step growth curve of viral replication shows a latent period. What occurs during this period?

Accepted Answer

Viral nucleic acid and proteins are synthesized, but no complete virions are detected outside the cell.

Question 6

Which of the following best explains why bacteriophage T4 is considered a model lytic virus?

Accepted Answer

It always kills the host cell by lysis after replication.

Question 7

Which of the following is a common receptor for bacteriophages on the surface of E. coli?

Accepted Answer

Lipopolysaccharide (LPS)

Question 8

A plant virus with a single-stranded RNA genome is most likely to have which of the following structures?

Accepted Answer

Helical capsid without an envelope

Question 9

Which enzyme is essential for the replication of retroviruses?

Accepted Answer

Reverse transcriptase

Question 10

In the context of SARS-CoV-2, what is the primary function of the spike (S) protein?

Accepted Answer

To facilitate attachment and entry into host cells by binding to the ACE2 receptor

Question 11

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

Accepted Answer

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

Question 12

Which of the following is a key difference between the replication of animal viruses and bacteriophages?

Accepted Answer

Animal viruses often enter host cells by membrane fusion or endocytosis, while bacteriophages inject their genome into the host.

Question 13

A viral plaque assay is used to:

Accepted Answer

Quantify the number of infectious virus particles in a sample.

Question 14

Which of the following best explains why enveloped viruses are generally more sensitive to disinfectants than naked viruses?

Accepted Answer

Their lipid envelope is disrupted by solvents and detergents.

Question 15

Which step in the lytic replication cycle of a bacteriophage involves the synthesis of viral nucleic acid and proteins?

Accepted Answer

Synthesis

Question 16

A virus that causes the formation of syncytia in infected cells is most likely to have which of the following properties?

Accepted Answer

It encodes a spike protein that mediates cell-cell fusion.

Question 17

Which of the following equations correctly represents the calculation of viral titer using a plaque assay?

Accepted Answer

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

Question 18

Which of the following best describes the function of the packaging motor in bacteriophage T4 assembly?

Accepted Answer

It translocates viral DNA into the preformed capsid using ATP.

Question 19

Which of the following scenarios best illustrates the concept of viral host specificity?

Accepted Answer

A bacteriophage infects only E. coli cells due to specific receptor recognition.

Question 20

Which of the following is a real-world consequence of lysogenic conversion in bacteria?

Accepted Answer

Bacteria acquire new traits, such as toxin production, due to prophage genes.

Chapter Five

Study Guide - Practice Questions