Question 1

Which of the following best describes the function of a promoter in gene expression?

Accepted Answer

A DNA sequence where RNA polymerase binds to initiate transcription.

Question 2

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; it introduces a premature stop codon, likely truncating the protein.

Question 3

Which of the following best explains why the lac operon is only expressed in the presence of lactose and absence of glucose?

Accepted Answer

Lactose inactivates the repressor, and low glucose increases cAMP, which activates CAP to promote transcription.

Question 4

During PCR (Polymerase Chain Reaction), which enzyme is responsible for synthesizing new DNA strands?

Accepted Answer

DNA polymerase

Question 5

A patient is diagnosed with tuberculosis. Which genus of bacteria is responsible for this disease, and what is a key feature of its cell wall?

Accepted Answer

Mycobacterium; contains mycolic acids making it acid-fast.

Question 6

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

Accepted Answer

Lytic cycle results in host cell lysis and release of new virions, while lysogenic cycle integrates viral DNA into the host genome without immediate lysis.

Question 7

Which of the following is an example of mutualism in the human microbiota?

Accepted Answer

Gut bacteria synthesize vitamins for the host while receiving nutrients and a stable environment.

Question 8

Which of the following best explains the role of restriction enzymes in molecular genetics?

Accepted Answer

They cut DNA at specific sequences, allowing for gene cloning and analysis.

Question 9

A Gram-negative bacterium is identified in a clinical sample. Which of the following characteristics would you expect?

Accepted Answer

Thin peptidoglycan layer and an outer membrane containing lipopolysaccharide.

Question 10

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It brings specific amino acids to the ribosome according to the codon sequence on mRNA.

Question 11

Which of the following is a correct sequence of steps in animal virus replication?

Accepted Answer

Attachment, penetration, uncoating, replication, assembly, release

Question 12

Which of the following best explains why PCR requires a heat-stable DNA polymerase?

Accepted Answer

The high temperatures used to denature DNA would inactivate most enzymes, but heat-stable polymerase remains active.

Question 13

Which of the following is a defining feature of eukaryotic cells compared to prokaryotic cells?

Accepted Answer

Presence of membrane-bound organelles such as the nucleus and mitochondria.

Question 14

A patient presents with a superficial fungal infection. Which of the following genera is most likely responsible?

Accepted Answer

Trichophyton

Question 15

Which of the following best describes the process of conjugation in bacteria?

Accepted Answer

Transfer of genetic material through direct cell-to-cell contact via a pilus.

Question 16

Which of the following is a correct example of a negative control in gene regulation?

Accepted Answer

A repressor protein binds to the operator to block transcription.

Question 17

Which of the following best describes the role of cAMP in the regulation of the lac operon?

Accepted Answer

cAMP binds to CAP, allowing it to activate transcription of the lac operon when glucose is low.

Question 18

Which of the following is a correct statement about the structure of a typical virus?

Accepted Answer

It consists of a nucleic acid genome surrounded by a protein capsid, and may have an envelope.

Question 19

Which of the following best explains why antibiotic resistance genes can spread rapidly among bacterial populations?

Accepted Answer

Horizontal gene transfer mechanisms such as conjugation, transformation, and transduction facilitate the spread of resistance genes.

Microbial Genetics, Classification, Viruses, and Eukaryotic Microorganisms: Study Notes

Study Guide - Practice Questions

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