Q: Which of the following equations best represents the burst size in a viral growth curve?

$$\text{Burst size} = \frac{\text{Number of virions released}}{\text{Number of infected cells}}$$

Question 1

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

Accepted Answer

They require host cell machinery for replication because they lack their own metabolic enzymes.

Question 2

Which experiment led to the discovery that viruses could pass through filters that trap bacteria, as shown in the image with the tobacco mosaic virus?

Accepted Answer

Ivanowski and Beijerinck's filtration of infected plant sap

Question 3

Which viral structure is responsible for recognizing and binding to specific host cell receptors, thus determining tissue tropism?

Accepted Answer

Spike protein

Question 4

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

Accepted Answer

Naked helical virus

Question 5

Which of the following best describes the lytic cycle of a bacteriophage?

Accepted Answer

The virus immediately takes over the host machinery, produces new virions, and lyses the host cell.

Question 6

During which stage of the lytic cycle does the viral genome enter the host cell cytoplasm?

Accepted Answer

Penetration

Question 7

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 8

Which of the following equations best represents the burst size in a viral growth curve?

Accepted Answer

$$	ext{Burst size} = \frac{	ext{Number of virions released}}{	ext{Number of infected cells}}$$

Question 9

Which of the following is a consequence of lysogenic conversion in bacteria?

Accepted Answer

The host cell gains new traits such as toxin production or resistance to further infection.

Question 10

Which of the following best explains why enveloped animal viruses can cause chronic infections?

Accepted Answer

They are released by budding, which does not destroy the host cell.

Question 11

A patient is infected with a +ssRNA virus. Which enzyme must the virus provide to replicate its genome?

Accepted Answer

RNA-dependent RNA polymerase

Question 12

Which of the following is NOT a characteristic of viruses?

Accepted Answer

They have their own metabolism.

Question 13

Which of the following best describes the difference between the lytic and lysogenic cycles?

Accepted Answer

The lytic cycle results in immediate host cell lysis, while the lysogenic cycle involves integration of viral DNA and delayed lysis.

Question 14

Which of the following is a plausible reason why some viruses are generalists and can infect multiple species?

Accepted Answer

Their surface proteins can bind to conserved receptors found in many species.

Question 15

Which of the following best describes the role of capsomeres in viral structure?

Accepted Answer

They are protein subunits that assemble to form the capsid.

Question 16

A scientist observes clear patches (plaques) on a bacterial lawn after adding a viral sample. What does this indicate?

Accepted Answer

The virus has lysed bacterial cells, creating areas of cell death.

Question 17

Which of the following best explains why most latent animal viruses do not integrate into the host genome?

Accepted Answer

They remain dormant in an inactive state within the host cell.

Question 18

Which of the following is the correct order of events in the lytic cycle of a bacteriophage?

Accepted Answer

Attachment, Penetration, Biosynthesis, Maturation, Lysis

Question 19

Which of the following best describes the function of viral enzymes found within some virions?

Accepted Answer

They assist in viral genome replication, especially in RNA viruses.

Question 20

Which of the following statements about viral genomes is correct?

Accepted Answer

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

Viruses: Structure, Classification, and Life Cycles - Micro L 3

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