Question 1

Which of the following best describes a virion?

Accepted Answer

A mature virus particle consisting of nucleic acid and a protein coat

Question 2

Viruses differ from bacteria in that viruses:

Accepted Answer

Are obligate intracellular parasites and lack metabolic machinery

Question 3

The host range of a virus is primarily determined by:

Accepted Answer

The presence of specific receptors on the host cell surface

Question 4

Which method is commonly used to identify viruses in clinical samples?

Accepted Answer

Polymerase chain reaction (PCR)

Question 5

Why must viruses be grown in living cells for culturing?

Accepted Answer

Viruses require host cell machinery for replication

Question 6

Which of the following is a key difference between DNA and RNA viruses?

Accepted Answer

DNA viruses use host DNA polymerase, while RNA viruses often use viral RNA-dependent RNA polymerase

Question 7

Which statement about prions is correct?

Accepted Answer

Prions are infectious proteins lacking nucleic acids

Question 8

During the lytic cycle of a bacteriophage, which event occurs first?

Accepted Answer

Attachment of the phage to the bacterial cell

Question 9

How does lysogeny influence the evolution of bacteria?

Accepted Answer

It allows horizontal gene transfer via prophage integration

Question 10

A patient presents with symptoms of Creutzfeldt-Jakob disease. Which agent is most likely responsible?

Accepted Answer

A prion

Question 11

Which of the following best describes the classification of viruses?

Accepted Answer

By their nucleic acid type, capsid structure, and presence of envelope

Question 12

In the lysogenic cycle, the viral genome:

Accepted Answer

Integrates into the host chromosome as a prophage

Question 13

Which scenario illustrates a multi-step problem involving viral identification and host range?

Accepted Answer

A virus is identified by PCR in a patient, and further analysis shows it infects only cells expressing CD4 receptors. What determines its host range?

Question 14

Which of the following equations represents the exponential increase in viral particles during the lytic cycle?

Accepted Answer

$$N = N_0$ 	imes 2^n$$

Question 15

A researcher is culturing viruses and observes no growth in nutrient broth. What is the most likely explanation?

Accepted Answer

Viruses require living cells for replication

Question 16

Which of the following is NOT a characteristic of viruses?

Accepted Answer

They can metabolize nutrients independently

Question 17

A virus infects a bacterium and integrates its DNA into the host genome. This process is called:

Accepted Answer

Lysogeny

Question 18

Which of the following best explains why prions are resistant to standard sterilization procedures?

Accepted Answer

Prions lack nucleic acids and are composed solely of misfolded proteins

Question 19

Which scenario best illustrates the application of viral classification in a medical context?

Accepted Answer

A physician orders PCR to determine if a patient is infected with an RNA virus or a DNA virus, which guides antiviral therapy

Question 20

Which of the following is a plausible consequence of lysogenic conversion in bacteria?

Accepted Answer

Acquisition of new virulence factors via prophage genes

Microbiology Study Guide: Viruses and Prions

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