Question 1

Which of the following best explains why viruses are not classified as living organisms in traditional Linnaean taxonomy?

Accepted Answer

They cannot metabolize or reproduce independently.

Question 2

A scientist discovers a new virus with a protein coat and a surrounding envelope derived from the host cell membrane. Which type of virus morphology does this describe?

Accepted Answer

Enveloped virus

Question 3

Which of the following statements about viral glycoproteins is correct?

Accepted Answer

They allow viruses to attach to specific host cell receptors.

Question 4

A virus with a single-stranded RNA genome that is directly used as mRNA for protein synthesis belongs to which Baltimore classification group?

Accepted Answer

Group IV (+ssRNA viruses)

Question 5

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

Accepted Answer

The host cell is destroyed as new viruses are produced and released.

Question 6

Why are RNA viruses, such as HIV and SARS-CoV-2, able to adapt rapidly to their hosts?

Accepted Answer

Their replication enzymes are error-prone, leading to frequent mutations.

Question 7

Which of the following is a key difference between the lytic and lysogenic cycles in bacteriophages?

Accepted Answer

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

Question 8

A patient is diagnosed with a viral infection. The virus is found to have a double-stranded DNA genome. Which of the following is most likely true about its replication?

Accepted Answer

The viral DNA is transcribed and translated using the host cell's enzymes.

Question 9

Which of the following best explains why vaccines are generally ineffective against viral infections once symptoms have appeared?

Accepted Answer

Vaccines are designed to prevent infection, not to treat active infections.

Question 10

Which of the following is a real-world example of a virus with a broad host range, infecting multiple species?

Accepted Answer

Rabies virus

Question 11

A retrovirus infects a host cell. Which of the following steps is unique to its replication cycle?

Accepted Answer

Reverse transcription of viral RNA to DNA

Question 12

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

Accepted Answer

They are protein subunits that form the viral capsid.

Question 13

A virus is classified as a negative-sense single-stranded RNA (-ssRNA) virus. What must occur before its genome can be translated by the host cell?

Accepted Answer

The -ssRNA must be transcribed to +mRNA by a viral RNA polymerase.

Question 14

Which of the following is a real-world consequence of the high mutation rate in RNA viruses?

Accepted Answer

RNA viruses can rapidly evolve resistance to antiviral drugs.

Question 15

Which of the following best explains why viral infections in plants often require mechanical damage to the cell wall for transmission?

Accepted Answer

The rigid plant cell wall prevents viral entry unless it is breached.

Question 16

A patient receives a vaccine containing a weakened but living virus. Which type of vaccine is this?

Accepted Answer

Live attenuated vaccine

Question 17

Which of the following best describes the role of viral nucleic acid in the viral lifecycle?

Accepted Answer

It encodes the information for making viral proteins and replicating the virus.

Question 18

Which of the following is a correct statement about the influenza virus?

Accepted Answer

Its subtypes are based on two surface proteins: hemagglutinin (H) and neuraminidase (N).

Question 19

Which of the following is a real-world example of a disease caused by a herpesvirus in non-human animals?

Accepted Answer

Fibropapillomatosis in sea turtles

Question 20

A virus infects a host cell and its genome is integrated into the host's DNA, remaining dormant for several generations. Which viral lifecycle does this describe?

Accepted Answer

Lysogenic cycle

Study Notes: Microbial Life – Viruses (Chapter 21)

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