Q: Which of the following equations correctly represents the process by which retroviruses synthesize DNA from their RNA genome?

$$\mathrm{RNA} \xrightarrow{\text{reverse transcriptase}} \mathrm{DNA}$$

Question 1

Which of the following statements best describes the host range of a virus?

Accepted Answer

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

Question 2

A virus with a helical capsid, an envelope, and spikes is most likely to be classified as which of the following?

Accepted Answer

An enveloped helical virus

Question 3

Which of the following best explains why viruses are considered obligate intracellular parasites?

Accepted Answer

They require living host cells to multiply.

Question 4

A scientist observes clear zones, or plaques, on a bacterial lawn after adding a viral sample. What is the most likely explanation for these plaques?

Accepted Answer

The virus has lysed the bacterial cells in these regions.

Question 5

Which of the following steps is unique to the multiplication of animal viruses compared to bacteriophages?

Accepted Answer

Penetration by endocytosis or fusion

Question 6

A patient presents with a maculopapular rash and later develops raised fluid-filled blisters. Which virus family is most likely responsible for this disease, and what is the name of the disease?

Accepted Answer

Poxviridae; smallpox

Question 7

Which of the following best describes the process of antigenic shift in influenza viruses?

Accepted Answer

The combination of genetic material from two different strains to form a new subtype

Question 8

Which of the following equations correctly represents the process by which retroviruses synthesize DNA from their RNA genome?

Accepted Answer

$$\mathrm{RNA} \xrightarrow{	ext{reverse transcriptase}} \mathrm{DNA}$$

Question 9

Which of the following is a characteristic of prions that distinguishes them from viruses?

Accepted Answer

They are composed solely of protein and lack nucleic acids.

Question 10

A virus is classified as a member of the family Herpesviridae. Which of the following is true about its structure and genome?

Accepted Answer

It is a double-stranded DNA virus with an envelope.

Question 11

Which of the following best explains why continuous cell lines are used for growing animal viruses in the laboratory?

Accepted Answer

They are transformed cells that can divide indefinitely and do not require a monolayer.

Question 12

During the lysogenic cycle of a bacteriophage, which of the following events occurs?

Accepted Answer

The phage DNA integrates into the host chromosome as a prophage.

Question 13

Which of the following is a correct match between a virus family and a disease it causes in humans?

Accepted Answer

Flaviviridae – West Nile virus

Question 14

A patient is diagnosed with a persistent viral infection that develops over many years and is ultimately fatal. Which of the following is the most likely example of such an infection?

Accepted Answer

Subacute sclerosing panencephalitis (measles virus)

Question 15

Which of the following best describes the process of specialized transduction?

Accepted Answer

A phage transfers specific bacterial genes adjacent to the prophage site to another bacterium.

Question 16

Which of the following is a correct statement about the taxonomy of viruses?

Accepted Answer

Family names end in -viridae.

Question 17

A virus is found to have a double-stranded DNA genome, is nonenveloped, and causes respiratory infections in humans. To which family does it most likely belong?

Accepted Answer

Adenoviridae

Question 18

Which of the following best explains the mechanism by which prions cause disease?

Accepted Answer

They convert normal cellular prion proteins into the abnormal form, leading to accumulation and cell death.

Question 19

Which of the following is a correct description of the release of enveloped animal viruses from host cells?

Accepted Answer

They are released by budding, acquiring their envelope from the host cell membrane.

Question 20

A virus is isolated that contains single-stranded RNA, is nonenveloped, and is known to cause poliomyelitis. Which family does this virus belong to?

Accepted Answer

Picornaviridae

Viruses: Structure, Classification, Multiplication, and Pathogenicity

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