Question 1

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

Accepted Answer

They can only replicate inside living host cells because they lack the necessary organelles and enzymes for independent life.

Question 2

A scientist is comparing the replication cycles of bacteriophages and animal viruses. Which of the following is a key difference between the two?

Accepted Answer

Animal viruses often enter host cells via endocytosis or membrane fusion, while bacteriophages inject their genetic material into the host.

Question 3

Which of the following statements about the viral envelope is correct?

Accepted Answer

The viral envelope is derived from the host cell's phospholipid bilayer and contains viral glycoproteins important for host cell recognition.

Question 4

A virus with a single-stranded RNA genome that serves directly as mRNA for protein synthesis is classified as which type of virus?

Accepted Answer

Positive-sense RNA virus

Question 5

During the lytic replication cycle of a bacteriophage, what is the correct order of the main steps?

Accepted Answer

Attachment, entry, synthesis, assembly, release

Question 6

Which of the following best explains the burst size in the context of the lytic cycle?

Accepted Answer

The number of new virions released from a single lysed bacterial cell

Question 7

A patient is diagnosed with a latent viral infection. Which of the following best describes the state of the virus in this scenario?

Accepted Answer

The viral genome is integrated into the host cell's DNA and remains dormant until reactivation.

Question 8

Which of the following is a unique feature of retroviruses such as HIV?

Accepted Answer

They use reverse transcriptase to synthesize DNA from an RNA template.

Question 9

A virus infects only plant cells and has a helical capsid with no envelope. Which of the following characteristics is most likely true for this virus?

Accepted Answer

It is likely to be transmitted via mechanical means such as insect vectors.

Question 10

Which of the following best describes the process of uncoating in animal virus replication?

Accepted Answer

The viral capsid is removed, releasing the viral genome into the host cell.

Question 11

A researcher observes that a certain virus can infect both humans and pigs. Which term best describes this virus's host range?

Accepted Answer

Broad host range

Question 12

Which of the following is NOT a criterion used to classify viruses?

Accepted Answer

Ability to metabolize glucose

Question 13

Which of the following equations best represents the relationship between the number of infected cells ($$N$$), burst size ($$B$$), and total number of new virions produced ($$V) in a $$lytic infection?

Accepted Answer

$$V = N 	imes B$$

Question 14

A negative-sense RNA virus must carry which of the following enzymes within its virion to ensure successful replication in the host cell?

Accepted Answer

RNA-dependent RNA polymerase

Question 15

Which of the following best explains why enveloped viruses are generally more sensitive to detergents and desiccation than non-enveloped viruses?

Accepted Answer

Detergents disrupt the phospholipid bilayer of the envelope, inactivating the virus.

Question 16

Which of the following steps is unique to the lysogenic cycle of bacteriophage replication?

Accepted Answer

Integration of the viral genome into the host cell's chromosome

Question 17

A patient is infected with influenza virus. Which enzyme is essential for the replication of the viral genome?

Accepted Answer

RNA-dependent RNA polymerase

Question 18

Which of the following best describes the function of viral glycoproteins found in the envelope of animal viruses?

Accepted Answer

They mediate attachment and entry into specific host cells by binding to cellular receptors.

Question 19

A virus is found to have a segmented genome. Which of the following is a potential consequence of this genome structure?

Accepted Answer

It can undergo reassortment, leading to rapid genetic variation.

Question 20

Which of the following best explains why viruses are not classified as living organisms?

Accepted Answer

They lack cellular structure and cannot carry out metabolism independently.

Viruses: Structure, Replication, and Classification (MIC 205 - Microbiology)

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