Question 1

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

Accepted Answer

They require host cell machinery to replicate their genetic material and produce new virions.

Question 2

A bacteriophage infects a bacterial cell and integrates its DNA into the host genome, remaining dormant for several generations. What is this process called?

Accepted Answer

Lysogenic cycle

Question 3

Which of the following structures is found in all viruses?

Accepted Answer

Capsid

Question 4

During the replication of animal viruses, which step is unique compared to bacteriophage replication?

Accepted Answer

Uncoating

Question 5

A scientist is preparing to grow influenza virus for vaccine production. Which of the following is the most appropriate method?

Accepted Answer

Grow the virus in living animal cells.

Question 6

Which of the following best explains why viruses cannot be grown on standard bacterial culture media?

Accepted Answer

Viruses require living cells to replicate because they lack metabolic machinery.

Question 7

Which viral morphology is described as having a spiral arrangement of capsomeres around the nucleic acid?

Accepted Answer

Helical capsid

Question 8

A patient is infected with a virus that remains dormant in their cells and reactivates years later during immunosuppression. What type of infection is this?

Accepted Answer

Latent viral infection

Question 9

Which of the following is NOT a step in the lytic cycle of bacteriophage replication?

Accepted Answer

Integration of viral DNA into host genome

Question 10

What is the main function of the viral capsid?

Accepted Answer

To protect the viral nucleic acid from degradation

Question 11

Which of the following equations correctly represents the exponential growth of viruses in a permissive cell culture, assuming each infected cell produces $$n$$ new virions per cycle and there are $$N_0$$ infected cells initially after $$t$$ cycles?

Accepted Answer

$$N = N_0$ 	imes n^t$$

Question 12

Which of the following best describes the difference between enveloped and non-enveloped viruses during the release step?

Accepted Answer

Enveloped viruses acquire their envelope from the host cell membrane during budding.

Question 13

A virus infects only respiratory epithelial cells in humans. This specificity is referred to as:

Accepted Answer

Tropism

Question 14

Which of the following is a correct sequence of steps in animal virus replication?

Accepted Answer

Attachment, Penetration, Uncoating, Biosynthesis, Maturation, Release

Question 15

Which of the following is a plausible reason why bacteriophages are used in phage therapy to treat bacterial infections?

Accepted Answer

Bacteriophages specifically infect and lyse bacterial cells without harming human cells.

Question 16

Which of the following best explains why only specific types of cells are infected by a given virus?

Accepted Answer

Viral surface proteins must match specific receptors on the host cell membrane.

Question 17

A researcher observes that a virus has an icosahedral capsid. Which of the following best describes the structure?

Accepted Answer

A capsid with 20 triangular faces forming a roughly spherical shape.

Question 18

Which of the following is a correct statement about the biosynthesis step in viral replication?

Accepted Answer

Viral nucleic acid directs the host cell to synthesize viral proteins and replicate viral genome.

Question 19

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

Accepted Answer

The lysogenic cycle involves integration of viral DNA into the host genome, while the lytic cycle results in immediate destruction of the host cell.

Fundamentals of Viruses: Structure, Cultivation, and Replication

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