Question 1

Which of the following best describes a fundamental difference between viruses and bacteria?

Accepted Answer

Viruses are obligate intracellular parasites, whereas bacteria can reproduce independently.

Question 2

A scientist is studying a virus that infects only a specific species of bird. This limitation is best described as the virus's:

Accepted Answer

Host range

Question 3

Which component of a virion is responsible for protecting the viral nucleic acid and determining the virus's shape?

Accepted Answer

Capsid

Question 4

A virus with a helical capsid and no envelope would be classified as which of the following?

Accepted Answer

Helical virus

Question 5

Which of the following best describes the structure of a complex virus such as a bacteriophage?

Accepted Answer

It has a polyhedral head and a helical tail.

Question 6

In a laboratory, which method is most commonly used to culture animal viruses?

Accepted Answer

Inoculation into living cell cultures

Question 7

During the lytic cycle of a bacteriophage, which step immediately follows the attachment of the phage to the bacterial cell?

Accepted Answer

Penetration of the phage DNA into the host cell

Question 8

Which of the following events is unique to the lysogenic cycle of bacteriophage multiplication?

Accepted Answer

Integration of phage DNA into the host genome as a prophage

Question 9

Phage conversion refers to:

Accepted Answer

A change in the phenotype of a bacterium due to the presence of a prophage

Question 10

A patient is infected with a virus that enters the host cell by fusion with the plasma membrane. Which step must occur before viral replication can begin?

Accepted Answer

Uncoating of the viral nucleic acid

Question 11

Which of the following best explains why the synthesis of nucleic acids during viral replication differs among viruses?

Accepted Answer

The type of viral genome (DNA or RNA) determines the synthesis process.

Question 12

During the maturation and release stage of animal virus replication, which process is most likely to occur in enveloped viruses?

Accepted Answer

Budding from the host cell membrane

Question 13

Oncogenic viruses are best defined as viruses that:

Accepted Answer

Can induce cancer in host cells

Question 14

Which of the following is a prion disease, and what is the primary mechanism by which prions cause disease?

Accepted Answer

Creutzfeldt-Jakob disease; prions induce abnormal folding of normal proteins

Question 15

A researcher observes that a virus has spikes on its surface. What is the most likely function of these spikes?

Accepted Answer

Attachment to specific host cell receptors

Question 16

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome. The bacterial cell continues to divide, passing the phage DNA to its progeny. This process is best described as:

Accepted Answer

Lysogeny

Question 17

Which of the following equations best represents the burst size in a lytic bacteriophage infection, where $$N_{total} is $$the total number of phages released and $$N_{infected} is $$the number of infected cells?

Accepted Answer

$$Burst\ Size = \frac{N_{total}}{N_{infected}}$$

Question 18

A hospital outbreak is traced to a virus that can only be visualized with an electron microscope and is approximately 100 nm in diameter. Which statement best explains why this virus cannot be seen with a light microscope?

Accepted Answer

The wavelength of visible light is too large to resolve objects as small as 100 nm.

Question 19

A patient is diagnosed with a prion disease after consuming contaminated beef. Which of the following best explains why standard sterilization procedures may fail to inactivate prions?

Accepted Answer

Prions are highly resistant to heat and standard chemical disinfectants.

Question 20

A virologist is comparing the replication cycles of a DNA virus and an RNA virus. Which of the following is a key difference in their replication strategies?

Accepted Answer

DNA viruses typically replicate in the host cell nucleus, while RNA viruses often replicate in the cytoplasm.

Study Guide: Viruses, Bacteriophages, and Prions (Microbiology Chapter 13)

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