Question 1

Which of the following best describes the role of sigma factors in prokaryotic transcription?

Accepted Answer

They bind to the -10 and -35 regions of the promoter to help RNA polymerase recognize where to start transcription.

Question 2

A bacterial cell is exposed to both glucose and lactose. Which of the following best describes the state of the lactose operon under these conditions?

Accepted Answer

The operon is off because the presence of glucose inhibits cAMP production, preventing CAP from activating transcription.

Question 3

Which enzyme is primarily responsible for synthesizing the leading strand during DNA replication in bacteria?

Accepted Answer

DNA Polymerase III

Question 4

A mutation occurs in the -10 region of a prokaryotic promoter. What is the most likely effect on gene expression?

Accepted Answer

Transcription initiation will be reduced or abolished because RNA polymerase cannot efficiently bind the promoter.

Question 5

Which of the following best explains why DNA Polymerase V is used during SOS repair in bacteria?

Accepted Answer

DNA Polymerase V can synthesize DNA across damaged regions that other polymerases cannot, though it is more error-prone.

Question 6

Which of the following is a real-world example of lysogenic conversion in bacteria?

Accepted Answer

Corynebacterium diphtheriae producing diphtheria toxin only when infected by a specific bacteriophage.

Question 7

A scientist is studying a bacterial strain that is His-. What does this mean, and how could this strain be used in a laboratory test for carcinogens?

Accepted Answer

The strain cannot synthesize histidine and can be used in the Ames test to detect mutagens that restore the ability to grow without histidine.

Question 8

Which of the following statements about transformation, transduction, and conjugation is correct?

Accepted Answer

Transformation involves uptake of naked DNA from the environment, transduction involves DNA transfer by bacteriophages, and conjugation requires direct cell-to-cell contact.

Question 9

Which of the following best describes the function of restriction enzymes in bacteria?

Accepted Answer

They cut foreign DNA at specific sequences, protecting the cell from viral infection.

Question 10

A virus with a helical capsid and an envelope is most likely to:

Accepted Answer

Have a lipid bilayer derived from the host cell membrane and a rod-shaped protein shell.

Question 11

Which of the following nucleic acids can be directly translated by host ribosomes without further modification?

Accepted Answer

Sense (+) RNA

Question 12

During a productive bacteriophage infection, which sequence of events occurs?

Accepted Answer

Attachment, injection of phage DNA, synthesis of early proteins, replication of phage DNA, assembly, and lysis of the host cell.

Question 13

Which of the following best explains how CRISPR-Cas protects bacteria from viral infection?

Accepted Answer

It uses crisprRNA to guide Cas9 to viral DNA sequences, which are then cut and inactivated.

Question 14

Which of the following is a key difference between acute and persistent animal virus infections?

Accepted Answer

Acute infections are characterized by rapid onset and clearance, while persistent infections involve long-term presence of the virus in the host.

Question 15

Which of the following best describes the role of the spike glycoprotein in SARS-CoV-2 infection?

Accepted Answer

It binds to the ACE2 receptor on host cells, facilitating viral entry.

Question 16

A bacterial cell is described as competent. What does this mean?

Accepted Answer

It is able to take up naked DNA from its environment.

Question 17

Which of the following best explains how a transposon can cause a mutation in a gene?

Accepted Answer

By inserting itself into the coding region of a gene, disrupting its function.

Question 18

Which of the following is true regarding the difference between monocistronic and polycistronic mRNA?

Accepted Answer

Monocistronic mRNA encodes a single protein and is typical of eukaryotes, while polycistronic mRNA encodes multiple proteins and is common in prokaryotes.

Question 19

Which of the following best describes the function of the modification gene in bacteria?

Accepted Answer

It encodes an enzyme that methylates the host's own DNA, protecting it from cleavage by restriction enzymes.

Question 20

A patient is diagnosed with a persistent viral infection that is characterized by periods of latency and reactivation. Which virus is most likely responsible for this type of infection?

Accepted Answer

Herpes simplex virus

Microbial Genetics and Virology Study Guide – Step-by-Step Guidance

Study Guide - Practice Questions

Study Guide - Flashcards