Q: Which of the following equations correctly represents the size range of most viruses?

$$20 \mathrm{\ nm} \leq \text{virus size} \leq 400 \mathrm{\ nm}$$

Question 1

Which of the following best describes why viruses are considered nonliving pathogens?

Accepted Answer

They lack cellular structure and cannot carry out metabolism on their own.

Question 2

A scientist discovers a new virus that infects only one species of bird. Which term best describes this virus's host range?

Accepted Answer

Narrow tropism

Question 3

Which structural feature is found in all viruses and is responsible for protecting the viral genome?

Accepted Answer

Capsid

Question 4

What is the main difference between enveloped and naked viruses regarding their release from host cells?

Accepted Answer

Enveloped viruses bud off the host cell, acquiring a lipid membrane; naked viruses lyse (burst) the host cell.

Question 5

Which of the following statements about bacteriophages is correct?

Accepted Answer

They lyse host cells and are always naked viruses.

Question 6

A virus with a helical capsid structure would most likely appear as:

Accepted Answer

A hollow tube

Question 7

Which viral component is primarily responsible for host cell recognition and attachment?

Accepted Answer

Spike proteins (peplomers)

Question 8

Influenza viruses frequently mutate and experience small changes in their spike proteins. This process is known as:

Accepted Answer

Antigenic drift

Question 9

Which two glycoproteins are found as spikes on the surface of influenza A viruses?

Accepted Answer

Hemagglutinin (HA) and Neuraminidase (NA)

Question 10

A virus is described as having a single-stranded RNA genome and lacking an envelope. Which of the following best describes its likely method of exiting the host cell?

Accepted Answer

Lysing (bursting) the host cell

Question 11

Which of the following is NOT a criterion used by the International Committee on Taxonomy of Viruses to classify viruses?

Accepted Answer

Ability to metabolize glucose

Question 12

If a virus has a genome architecture described as dsDNA, what does this mean?

Accepted Answer

The virus has a double-stranded DNA genome.

Question 13

Which of the following equations correctly represents the size range of most viruses?

Accepted Answer

$$20 \mathrm{\ nm} \leq 	ext{virus size} \leq 400 \mathrm{\ nm}$$

Question 14

Which of the following best explains why RNA viruses tend to evolve faster than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading ability, leading to higher mutation rates.

Question 15

A pandemic can result when a virus undergoes antigenic shift. What is the main consequence of antigenic shift?

Accepted Answer

Increased infectivity and expanded host range

Question 16

Which of the following best describes the role of capsomers in viral structure?

Accepted Answer

They are protein subunits that make up the capsid.

Question 17

A virus is found to infect both humans and pigs. What does this indicate about its host range?

Accepted Answer

It has a broad tropism.

Question 18

Which of the following is true regarding viral taxonomy?

Accepted Answer

The highest taxonomic level for viruses is the phylum.

Question 19

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

Accepted Answer

It causes minor changes in viral antigens, requiring annual updates to vaccines.

Question 20

Which of the following best describes the function of viral spikes (peplomers)?

Accepted Answer

They mediate attachment to specific host cell receptors.

chap 6A

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