Question 1

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

Accepted Answer

The lytic cycle results in the immediate production and release of new phages, while the lysogenic cycle allows viral DNA to remain dormant within the host genome.

Question 2

A virus that contains RNA as its genetic material and uses reverse transcriptase to synthesize DNA is classified as a:

Accepted Answer

Retrovirus

Question 3

Which of the following steps is unique to the reproductive cycle of retroviruses such as HIV?

Accepted Answer

Reverse transcription of viral RNA into DNA

Question 4

Why are antibiotics ineffective against viral infections such as influenza?

Accepted Answer

Viruses do not carry out metabolic processes targeted by antibiotics.

Question 5

Which of the following diseases is caused by a DNA virus?

Accepted Answer

Hepatitis B

Question 6

A prophage is best described as:

Accepted Answer

Viral DNA that has been integrated into the bacterial chromosome

Question 7

Which of the following events can trigger a prophage to exit the bacterial chromosome and enter the lytic cycle?

Accepted Answer

Environmental signals such as radiation or certain chemicals

Question 8

Plant viruses most commonly enter plant cells through:

Accepted Answer

Wounds in the plant’s outer layers or transmission by insects

Question 9

Which of the following is a reason why the development of antiviral drugs is more challenging than the development of antibiotics?

Accepted Answer

Viruses use the host cell’s machinery for replication, making it difficult to target the virus without harming the host cell.

Question 10

Which of the following best explains why polio infections can result in permanent damage, while the common cold does not?

Accepted Answer

Polio infects cells that cannot divide, while cold viruses infect cells that can be replaced by mitosis.

Question 11

Which of the following processes contributes to the emergence of new viral diseases?

Accepted Answer

Contact between species, mutations, and spread from isolated populations

Question 12

In the reproductive cycle of an enveloped RNA virus, what is the role of glycoprotein spikes?

Accepted Answer

They attach to receptor proteins on the host cell membrane, facilitating entry.

Question 13

Which of the following is a correct sequence of events for HIV replication in a host cell?

Accepted Answer

Entry → Reverse transcription → Integration into host DNA → Transcription → Translation → Assembly → Exit

Question 14

Which of the following statements about the structure of viruses is correct?

Accepted Answer

All viruses consist of nucleic acid surrounded by a protein coat, and some have an additional membranous envelope.

Question 15

A patient is diagnosed with a disease caused by a lysogenic bacteriophage. Which of the following best explains how the disease symptoms might arise?

Accepted Answer

Prophage genes direct the host bacterium to produce toxins.

Question 16

Which of the following best describes why there are no cures for most viral diseases of plants and animals?

Accepted Answer

Viruses use host cell machinery, making it difficult to target the virus without harming the host.

Question 17

Which of the following is a real-world example of a disease caused by a prophage gene in bacteria?

Accepted Answer

Scarlet fever

Question 18

If a scientist is breeding plants resistant to viral infections, which of the following strategies would be most effective?

Accepted Answer

Selecting plants with mutations that prevent viral entry through wounds or insect transmission

Question 19

Which of the following equations best represents the process catalyzed by reverse transcriptase in retroviruses?

Accepted Answer

$$RNA \rightarrow DNA$$

Question 20

A virus is considered non-living because:

Accepted Answer

It cannot reproduce on its own and lacks cellular structure.

Microbial Genetics: Viruses and Their Reproductive Cycles

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