Question 1

Which of the following statements best distinguishes viruses, viroids, and prions from cellular life forms?

Accepted Answer

They all lack cell membranes and are considered acellular.

Question 2

A scientist observes a structure consisting of a protein coat surrounding a nucleic acid core, but no cell membrane. What is the correct term for this structure when it is outside a host cell?

Accepted Answer

Virion

Question 3

During the lytic cycle of T4 bacteriophage, which enzyme is responsible for degrading the bacterial cell wall to allow release of new virions?

Accepted Answer

Lysozyme

Question 4

Which of the following best describes the process of lysogenic conversion?

Accepted Answer

A harmless bacterium becomes pathogenic due to the integration of a prophage.

Question 5

A naked virus infects a host cell by creating a pore in the cytoplasmic membrane and injecting its genome, leaving the capsid outside. What is this entry mechanism called?

Accepted Answer

Direct penetration

Question 6

Which of the following viruses uses reverse transcriptase to synthesize DNA from an RNA template during its replication cycle?

Accepted Answer

Hepatitis B virus

Question 7

A patient is diagnosed with a persistent viral infection in which the host cells continuously shed viruses over time. Which release mechanism is most likely responsible?

Accepted Answer

Budding

Question 8

Which of the following best describes the genome of a retrovirus such as HIV?

Accepted Answer

Single-stranded RNA that is reverse transcribed into DNA

Question 9

A researcher is studying a virus that uses its genome directly as mRNA upon infection. Which type of viral genome does this virus most likely possess?

Accepted Answer

+ssRNA

Question 10

Which of the following is true regarding the naming of viral families?

Accepted Answer

They are usually written in italics and English, not Latin.

Question 11

During the lytic cycle of T4 bacteriophage, what is the term for the time required from initial attachment to the release of new virions?

Accepted Answer

Burst time

Question 12

Which of the following best explains why plaques appear on a bacterial lawn after infection with a lytic bacteriophage?

Accepted Answer

Areas where bacteria have been lysed by released virions

Question 13

A virus enters a host cell by fusing its envelope with the host's cytoplasmic membrane, releasing the capsid into the cytoplasm. Which virus is most likely to use this mechanism?

Accepted Answer

Measles virus

Question 14

Which of the following statements about prions is correct?

Accepted Answer

They are cytoplasmic membrane proteins found in mammalian brain cells.

Question 15

A scientist is studying a dsDNA virus that infects E. coli and can integrate its genome into the host chromosome, remaining inactive for several generations. What is the term for the integrated viral DNA?

Accepted Answer

Prophage

Question 16

Which of the following best describes the process of induction in the lysogenic cycle?

Accepted Answer

The prophage is excised from the host chromosome and enters the lytic phase.

Question 17

A virus with a single-stranded DNA genome infects a host cell. Which enzyme is responsible for synthesizing mRNA complementary to the viral genome?

Accepted Answer

Cellular RNA polymerase

Question 18

Which of the following is a correct pairing of viral genome type and an example virus?

Accepted Answer

-ssRNA: Rabies virus

Question 19

A researcher is measuring the number of new virions released from each lysed bacterium after infection with a lytic phage. What is this value called?

Accepted Answer

Burst size

Question 20

Which of the following best explains why virions are nonmotile and how they encounter host cells?

Accepted Answer

They rely on random collisions to contact host cells.

Characterizing and Classifying Viruses, Virions, and Prions

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