Question 1

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

Accepted Answer

They require host cell machinery to replicate their genome and synthesize proteins.

Question 2

A scientist is attempting to culture a newly discovered virus. Which of the following methods would be most appropriate for growing this virus in the laboratory?

Accepted Answer

Inoculating the virus into a living host cell culture.

Question 3

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

Accepted Answer

A genome of either DNA or RNA surrounded by a protein capsid.

Question 4

The Chamberland filter played a crucial role in the discovery of viruses because:

Accepted Answer

It allowed scientists to demonstrate that infectious agents smaller than bacteria could pass through and still cause disease.

Question 5

Which of the following is a key difference between the lytic and lysogenic cycles of bacteriophage replication?

Accepted Answer

The lytic cycle results in the destruction of the host cell, while the lysogenic cycle allows the viral genome to persist in the host without killing it.

Question 6

A virus with a single-stranded negative-sense RNA genome must carry which of the following enzymes within its capsid to be infectious?

Accepted Answer

RNA-dependent RNA polymerase

Question 7

Which of the following best explains why prions are unique among infectious agents?

Accepted Answer

They are composed solely of protein and lack nucleic acids.

Question 8

A patient is diagnosed with a disease caused by a retrovirus. Which of the following steps is essential for the replication of this virus?

Accepted Answer

Reverse transcription of viral RNA into DNA by reverse transcriptase.

Question 9

Which of the following best describes the function of the viral envelope in animal viruses?

Accepted Answer

It facilitates attachment and entry into host cells by fusing with the host membrane.

Question 10

A researcher is studying a virus that can infect both birds and humans. This virus is best described as having:

Accepted Answer

A broad host range.

Question 11

Which of the following is a correct statement about viroids?

Accepted Answer

They are small, circular pieces of RNA that infect plants.

Question 12

Which of the following best explains why viruses cannot be classified as living organisms?

Accepted Answer

They cannot carry out metabolic processes or reproduce independently.

Question 13

A scientist is using a scanning electron microscope (SEM) to study viruses. What is the main advantage of using SEM over a light microscope for this purpose?

Accepted Answer

SEM can resolve structures smaller than 200 nm, allowing visualization of viruses.

Question 14

Which of the following best describes the process of budding in enveloped animal viruses?

Accepted Answer

The virus acquires its envelope from the host cell membrane as it exits the cell.

Question 15

Which of the following is a common feature of all viral genomes?

Accepted Answer

They can be either DNA or RNA, but never both.

Question 16

A patient develops a neurodegenerative disease after consuming contaminated meat. Which infectious agent is most likely responsible?

Accepted Answer

A prion

Question 17

Which of the following best explains why prion diseases are difficult to control in healthcare settings?

Accepted Answer

Prions are resistant to most sterilization methods and can survive standard disinfection.

Question 18

Which of the following is a key step in the replication of a double-stranded DNA (dsDNA) animal virus?

Accepted Answer

Replication of viral DNA in the nucleus using host cell enzymes.

Question 19

Which of the following best describes the role of oncogenes in cancer development?

Accepted Answer

Oncogenes promote uncontrolled cell growth and can lead to cancer.

Question 20

A scientist is studying a virus with a segmented, double-stranded RNA genome. Which of the following best describes the replication strategy of this virus?

Accepted Answer

The virus must carry an RNA-dependent RNA polymerase to synthesize mRNA from its genome.

Viruses, Viroids, and Prions: Tiny but Deadly (Chapter 13 Study Notes)

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