Question 1

Which of the following characteristics distinguishes viruses from bacteria?

Accepted Answer

Viruses lack ATP-generating mechanisms and must replicate inside living host cells.

Question 2

A scientist is studying a virus with a helical capsid, an envelope, and glycoprotein spikes. Which of the following best describes the structure of this virus?

Accepted Answer

It is an enveloped helical virus.

Question 3

Which of the following best explains why most viruses infect only specific types of cells in one host?

Accepted Answer

Viruses require specific host attachment sites and compatible cellular factors.

Question 4

Which of the following is the correct order of events in the lytic cycle of a T-even bacteriophage?

Accepted Answer

Attachment, penetration, biosynthesis, maturation, release

Question 5

A virus is classified as a member of the family Herpesviridae. What is the correct ending for its genus name?

Accepted Answer

-virus

Question 6

Which laboratory method is most appropriate for quantifying the number of infectious bacteriophage particles in a sample?

Accepted Answer

Counting plaques on a bacterial lawn (plaque assay)

Question 7

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophage lambda?

Accepted Answer

The lytic cycle results in immediate lysis of the host cell, while the lysogenic cycle involves integration of phage DNA as a prophage.

Question 8

Which of the following viruses is correctly matched with its genome type and associated disease?

Accepted Answer

Herpesviridae: double-stranded DNA, causes cold sores

Question 9

Which of the following best explains how an RNA virus such as Retroviridae can cause cancer?

Accepted Answer

The viral RNA is transcribed into DNA by reverse transcriptase, which integrates into the host genome as a provirus.

Question 10

Which of the following is a key feature of a persistent viral infection?

Accepted Answer

The virus is continuously released over a long period, often causing progressive disease.

Question 11

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that lack nucleic acids and can cause diseases such as Creutzfeldt-Jakob disease.

Question 12

A patient is diagnosed with hepatitis B. Which viral family does this virus belong to, and what is a unique feature of its replication?

Accepted Answer

Hepadnaviridae; uses reverse transcriptase to produce DNA from RNA

Question 13

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

Accepted Answer

Specific bacterial genes near the prophage integration site are transferred by a lysogenic phage.

Question 14

Which of the following is a correct statement about the biosynthesis of RNA viruses?

Accepted Answer

Positive-sense single-stranded RNA viruses can serve directly as mRNA for protein synthesis.

Question 15

Which of the following is a real-world example of a latent viral infection?

Accepted Answer

Cold sores caused by HHV-1

Question 16

Which of the following best describes how plant viruses typically enter host cells?

Accepted Answer

Through wounds or via insect vectors

Question 17

A viroid is best described as:

Accepted Answer

A short piece of naked RNA that infects plants

Question 18

Which of the following laboratory techniques would be most useful for identifying the presence of influenza virus in a patient sample?

Accepted Answer

Western blotting to detect viral proteins

Question 19

Which of the following equations correctly represents the calculation of plaque-forming units (PFU) in a viral plaque assay?

Accepted Answer

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

13 Viruses, Viroids, and Prions: Structure, Classification, and Replication

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