Question 1

Which of the following is a distinctive feature of viruses that differentiates them from bacteria?

Accepted Answer

Viruses are obligate intracellular parasites and require living host cells to multiply.

Question 2

A scientist is studying a virus with a helical capsid and an envelope. Which of the following viruses is most likely being studied?

Accepted Answer

Ebola virus

Question 3

Which statement best describes the host range of a virus?

Accepted Answer

Host range is determined by specific host attachment sites and cellular factors.

Question 4

Which component of a virus is responsible for its attachment to host cells?

Accepted Answer

Spikes

Question 5

A virus has a genome consisting of single-stranded RNA and is classified according to the Baltimore system. Which equation best represents the process by which its mRNA is produced?

Accepted Answer

$$\mathrm{ssRNA} \rightarrow \mathrm{mRNA}$$

Question 6

Which of the following best describes the structure of a polyhedral virus?

Accepted Answer

A many-sided capsid, most commonly an icosahedron with 20 triangular faces and 12 corners

Question 7

In the laboratory, bacteriophages are quantified using plaque-forming units (PFU). What does each plaque represent?

Accepted Answer

A single virus particle that has lysed a host cell

Question 8

Which of the following is true regarding the viral genome?

Accepted Answer

It may be linear, circular, or segmented.

Question 9

A researcher is growing animal viruses in the laboratory using embryonated eggs. What is a sign that the virus has replicated successfully?

Accepted Answer

Changes or death of the embryo

Question 10

Which of the following statements about the envelope of a virus is correct?

Accepted Answer

It is partially formed from the plasma membrane of the host cell when the virus buds from the cell.

Question 11

Which taxonomic suffix is used for the family names of viruses?

Accepted Answer

-viridae

Question 12

A virus is found to have spikes on its surface. What is the primary function of these spikes?

Accepted Answer

Attachment to host cells

Question 13

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

Accepted Answer

They lack ribosomes and cannot generate ATP.

Question 14

A virus infects only bacteria and has a complex structure with a head and tail fibers. Which type of virus is this?

Accepted Answer

Bacteriophage

Question 15

Which of the following is NOT a component of a virion?

Accepted Answer

Ribosome

Question 16

A virus is found to have a segmented genome. Which of the following is a possible consequence of this feature?

Accepted Answer

The virus can undergo genetic reassortment, leading to new viral strains.

Question 17

Which of the following best describes the Baltimore classification system for viruses?

Accepted Answer

It is based on the virus's nucleic acid and how its mRNA is produced.

Question 18

A scientist observes a virus with a hollow, cylindrical capsid. Which type of virus morphology is being observed?

Accepted Answer

Helical

Question 19

Which of the following laboratory methods is commonly used to grow viruses for vaccine production?

Accepted Answer

Injecting viruses into embryonated eggs

Question 20

A virus is found to have a capsid composed of protein subunits. What are these subunits called?

Accepted Answer

Capsomeres

Viruses: Structure, Classification, and Laboratory Cultivation

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