Question 1

Which of the following best describes the difference between enveloped and nonenveloped (naked) viruses?

Accepted Answer

Enveloped viruses have a lipid membrane derived from the host cell, while nonenveloped viruses lack this membrane.

Question 2

A virus with a segmented, single-stranded RNA genome is most likely to:

Accepted Answer

Undergo genetic reassortment, increasing its potential for rapid evolution.

Question 3

Which step in the viral life cycle is most variable among different types of viruses?

Accepted Answer

Synthesis of viral components

Question 4

The SARS-CoV-2 virus attaches to human cells using which specific interaction?

Accepted Answer

Its spike protein binding to the ACE2 receptor on host cells

Question 5

Which of the following is a unique feature of temperate bacteriophages compared to virulent phages?

Accepted Answer

They can integrate their genome into the host chromosome and establish lysogeny.

Question 6

Which of the following best explains why viruses are considered acellular?

Accepted Answer

They lack cellular structures such as ribosomes and a plasma membrane.

Question 7

A scientist is studying a virus with a helical capsid. Which of the following statements is most accurate?

Accepted Answer

The capsid is shaped like a hollow tube with protein walls formed by self-assembling protomers.

Question 8

Which of the following is a function of viral envelope proteins?

Accepted Answer

They mediate attachment to host cell receptors and may have enzymatic activity.

Question 9

Which of the following best describes the process of viral budding?

Accepted Answer

The viral nucleocapsid acquires its envelope by pinching off from the host cell membrane.

Question 10

Which of the following equations best represents the relationship between the number of protomers ($$n) $$and the length ($$L) of a $$helical viral capsid, assuming each protomer adds a fixed length $$d$$?

Accepted Answer

$$L = n 	imes d$$

Question 11

Which of the following is NOT a possible outcome of a viral infection in a eukaryotic cell?

Accepted Answer

Permanent immunity to all viruses

Question 12

Which of the following statements about viral genomes is correct?

Accepted Answer

They can be composed of either DNA or RNA, which may be single- or double-stranded.

Question 13

A bacteriophage is observed to inject only its genome into a bacterial cell, leaving the capsid outside. This is an example of which viral entry mechanism?

Accepted Answer

Direct injection of nucleic acid

Question 14

Which of the following best describes the role of bacteriophages in the human gut?

Accepted Answer

They help regulate the bacterial microbiome.

Question 15

Which of the following is a reason why viruses are important model systems in molecular biology?

Accepted Answer

Their simple structure and replication mechanisms allow for the study of fundamental biological processes.

Question 16

Which of the following statements about viral attachment is correct?

Accepted Answer

It involves specific interactions between viral ligands and host cell receptors.

Question 17

Which of the following best explains why plant viruses often require mechanical damage for entry into host cells?

Accepted Answer

Plant cells lack specific viral receptors on their surface.

Question 18

Which of the following is a plausible reason why viral envelope proteins are useful for virus identification?

Accepted Answer

They are virally encoded and often unique to each virus species.

Question 19

Which of the following best describes the process of lysogeny in temperate phages?

Accepted Answer

The viral genome integrates into the host genome and is replicated along with it without causing host cell lysis.

Question 20

Which of the following equations best represents the exponential increase in the number of virions ($$N) $$after $$n$$ replication cycles, if each cycle produces $$k$$ new virions per infected cell?

Accepted Answer

$$N = k^n$$

Viruses: Structure, Multiplication, and Roles in Microbiology

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