Q: Which equation correctly represents the size range of most viruses?

$$20 \, \text{nm} \u003c \text{size} \u003c 300 \, \text{nm}$$

Question 1

Which of the following best describes the main structural components of a typical virus?

Accepted Answer

A protein capsid, nucleic acid genome, and sometimes a lipid envelope

Question 2

A scientist is comparing two viruses. Virus A has a lipid envelope, while Virus B does not. Which of the following is most likely true about Virus A?

Accepted Answer

It acquires its envelope from the host cell membrane during budding

Question 3

Which equation correctly represents the size range of most viruses?

Accepted Answer

$$20 \, 	ext{nm} \u003c 	ext{size} \u003c 300 \, 	ext{nm}$$

Question 4

During the lytic cycle of a bacteriophage, which event occurs immediately after the viral genome enters the host cell?

Accepted Answer

The host cell's machinery begins to transcribe and translate viral genes

Question 5

Which of the following best distinguishes the lysogenic cycle from the lytic cycle in bacteriophages?

Accepted Answer

The lysogenic cycle involves integration of viral DNA into the host genome as a prophage

Question 6

A patient is infected with a virus that uses reverse transcriptase. Which of the following best describes the function of this enzyme?

Accepted Answer

It synthesizes DNA from an RNA template

Question 7

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that can cause neurodegenerative diseases

Question 8

Restriction enzymes are important in bacterial defense against viruses because they:

Accepted Answer

Cut foreign DNA at specific sequences, preventing viral replication

Question 9

Which of the following best explains why animal viruses often enter host cells by endocytosis, while bacteriophages inject their DNA?

Accepted Answer

Animal cells lack a cell wall, allowing viruses to be engulfed

Question 10

A scientist is studying a virus that can remain dormant in host cells for years before becoming active. Which viral replication cycle is most likely involved?

Accepted Answer

Lysogenic cycle

Question 11

Which of the following best describes the role of a prophage in the lysogenic cycle?

Accepted Answer

It is a viral genome integrated into the host's DNA

Question 12

Which of the following is a key difference between animal virus replication and bacteriophage replication?

Accepted Answer

Animal viruses often use budding to exit the host cell, while bacteriophages typically cause cell lysis

Question 13

A virus infects a host cell and uses the following process: $$	ext{RNA} ightarrow 	ext{DNA} ightarrow 	ext{mRNA} ightarrow 	ext{Protein}. $$Which type of virus is this?

Accepted Answer

Retrovirus

Question 14

Which of the following best explains why restriction enzymes are valuable tools in biotechnology?

Accepted Answer

They can cut DNA at specific sequences, allowing scientists to manipulate genes

Question 15

A patient is diagnosed with a disease caused by a prion. Which of the following is most likely to be observed in the patient's nervous system?

Accepted Answer

Accumulation of misfolded proteins leading to neurodegeneration

Question 16

Which of the following best describes the function of the capsid in a virus?

Accepted Answer

It protects the viral genome and aids in attachment to host cells

Question 17

A virus infects a bacterial cell and its DNA is immediately transcribed and translated by the host. Which cycle is this virus following?

Accepted Answer

Lytic cycle

Question 18

Which of the following is a correct statement about the host range of a virus?

Accepted Answer

It is determined by the virus's ability to bind specific receptors on the host cell surface

Question 19

Which of the following best explains why HIV is difficult to cure?

Accepted Answer

HIV integrates its genome into the host's DNA, forming a provirus that can remain dormant

Question 20

A researcher is studying a new virus and finds that it can infect both plant and animal cells. Which of the following is most likely true about this virus?

Accepted Answer

It recognizes conserved receptor molecules present on both plant and animal cells

Chapter 19: Viruses and Prions – Structure and Replication

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