Question 1

Which of the following best explains why viruses are not considered alive?

Accepted Answer

They cannot reproduce independently outside of a host cell.

Question 2

A scientist is studying a virus with a single-stranded RNA genome that can be directly translated by host ribosomes. Which type of viral genome does this virus most likely possess?

Accepted Answer

$+ssRNA$

Question 3

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause disease by inducing abnormal folding of normal cellular proteins.

Question 4

A patient is diagnosed with a disease caused by a prion. Which of the following is the most likely mechanism of disease progression?

Accepted Answer

The prion protein induces misfolding of normal proteins, leading to accumulation of abnormal proteins in neural tissue.

Question 5

Which of the following best describes the replication strategy of a $-ssRNA$ virus in a host cell?

Accepted Answer

It must carry an RNA-dependent RNA polymerase to synthesize $+ssRNA$ for translation.

Question 6

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

Accepted Answer

Viroids lack a protein capsid, while viruses have one.

Question 7

A researcher is culturing viruses in the laboratory. Which of the following methods is most likely to be used for animal viruses?

Accepted Answer

Growing viruses in cell (tissue) culture derived from animal cells.

Question 8

Which of the following best explains how some viruses can cause cancer in humans?

Accepted Answer

They encode proteins that interfere with normal cell cycle regulation, leading to uncontrolled cell growth.

Question 9

Which of the following is a property of enveloped viruses that distinguishes them from non-enveloped viruses?

Accepted Answer

They acquire their envelope from the host cell membrane during budding.

Question 10

A virus with a double-stranded DNA genome replicates in a host cell. Which of the following statements is most accurate regarding its replication?

Accepted Answer

Viral genome replication occurs in the nucleus, while viral proteins are synthesized in the cytoplasm.

Question 11

Which of the following best describes the function of viral oncogenes in cancer development?

Accepted Answer

They promote cell division by overriding normal growth control mechanisms.

Question 12

Which of the following is a correct statement about the destruction of prions?

Accepted Answer

Prions are highly resistant and require heating to $482^{\circ}C$ for four hours or autoclaving at $132^{\circ}C$ in concentrated sodium hydroxide for inactivation.

Question 13

A plant is infected by a pathogen that consists of a small, circular RNA molecule with no protein coat. Which type of infectious agent is most likely responsible?

Accepted Answer

Viroid

Question 14

Which of the following best explains why viruses cannot be grown on nutrient agar plates like bacteria?

Accepted Answer

Viruses require living host cells for replication.

Question 15

A patient is infected with a virus that integrates its genome into the host cell's DNA and remains dormant for years before causing symptoms. Which term best describes this type of infection?

Accepted Answer

Latent infection

Question 16

Which of the following is a common method for estimating the number of viruses in a sample?

Accepted Answer

Plaque assay

Question 17

Which of the following is a real-world example of a disease caused by a prion?

Accepted Answer

Creutzfeldt-Jakob disease

Question 18

A virus is found to cause cancer by integrating its DNA into the host genome and activating a proto-oncogene. Which of the following best describes the gene after activation?

Accepted Answer

Oncogene

Question 19

Which of the following is a plausible reason why growing viruses in whole animals or plants is less preferred than using cell culture?

Accepted Answer

It raises ethical and technical issues.

Question 20

Which of the following best describes the role of the viral envelope in infection?

Accepted Answer

It helps the virus evade the host immune system and facilitates entry into new host cells.

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

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