Question 1

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

Accepted Answer

They require host cell machinery to reproduce.

Question 2

A virus particle is called a virion. Which of the following components is always present in a virion?

Accepted Answer

A nucleic acid genome

Question 3

What is the function of spike proteins found on the surface of some viruses?

Accepted Answer

They allow the virus to attach to and enter host cells.

Question 4

Which statement correctly distinguishes between a naked virus and an enveloped virus?

Accepted Answer

Enveloped viruses possess a membrane composed of host-derived lipids and viral proteins.

Question 5

Which of the following is NOT one of the three basic shapes of viruses?

Accepted Answer

Spherical

Question 6

Why are RNA viruses more prone to antigenic drift compared to DNA viruses?

Accepted Answer

RNA viruses lack proofreading during replication, leading to higher mutation rates.

Question 7

Which enzyme is most important for the replication of RNA viruses?

Accepted Answer

RNA-dependent RNA polymerase

Question 8

A bacteriophage infects a bacterial cell. Which of the following is a major difference between bacteriophage infection and animal virus infection?

Accepted Answer

Bacteriophages inject their nucleic acid into the host, while animal viruses typically enter by endocytosis or membrane fusion.

Question 9

Which of the following best describes lysogenic conversion?

Accepted Answer

A bacterium acquires new traits due to the integration of viral DNA into its genome.

Question 10

Why does only Corynebacterium diphtheriae carrying a lysogenic phage produce diphtheria toxin?

Accepted Answer

The phage encodes the gene for diphtheria toxin, which is expressed only when integrated into the bacterial genome.

Question 11

Which of the following best describes a latent viral infection?

Accepted Answer

The virus remains dormant in the host cell and can reactivate later.

Question 12

Which of the following is required to culture a virus in the laboratory?

Accepted Answer

Living host cells

Question 13

Which equation best represents the process of reverse transcription in retroviruses?

Accepted Answer

$$RNA \rightarrow DNA \rightarrow RNA \rightarrow Protein$$

Question 14

Which of the following viruses is most likely to cause cancer in humans?

Accepted Answer

Human papillomavirus (HPV)

Question 15

What is a prion and how does it differ from a virus?

Accepted Answer

A prion is a misfolded protein that can induce abnormal folding in other proteins; it lacks nucleic acids unlike viruses.

Question 16

Which of the following best describes a persistent viral infection?

Accepted Answer

The virus remains in the host and produces infectious particles over a long period.

Question 17

Which step in the lytic cycle of a bacteriophage involves the synthesis of new viral components?

Accepted Answer

Biosynthesis

Question 18

Which of the following statements about viral classification is correct?

Accepted Answer

Viruses are classified based on the type of nucleic acid they possess.

Question 19

Which of the following is a correct statement about the replication of animal viruses?

Accepted Answer

Some animal viruses replicate in the cytoplasm, while others replicate in the nucleus.

Question 20

Which of the following is true regarding the naming of viruses?

Accepted Answer

Virus names often reflect the disease they cause or the host they infect.

Study Notes: Viruses and Prions (Microbiology Chapter 13)

Study Guide - Practice Questions