Question 1

Which of the following best describes the role of an inducible operon in prokaryotic transcription regulation?

Accepted Answer

It is turned off by default and only activated in the presence of a specific substrate.

Question 2

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

Accepted Answer

Nonsense mutation; the protein will be truncated and likely nonfunctional.

Question 3

Which process involves the transfer of DNA from one bacterium to another via a pilus?

Accepted Answer

Conjugation

Question 4

Which of the following is NOT a physical method of microbial control?

Accepted Answer

Quaternary ammonium compounds

Question 5

A hospital uses UV light to sterilize surgical instruments. What is the primary mechanism by which UV light kills microbes?

Accepted Answer

Induces thymine dimers in DNA, preventing replication

Question 6

Which of the following antimicrobial drugs inhibits cell wall synthesis?

Accepted Answer

Penicillin

Question 7

A patient is infected with a bacterium that produces beta-lactamase. Which drug would likely be ineffective?

Accepted Answer

Penicillin

Question 8

Which of the following best describes an opportunistic pathogen?

Accepted Answer

A microbe that causes disease only when the host's defenses are compromised.

Question 9

Which enzyme is responsible for cutting DNA at specific sequences during genetic engineering?

Accepted Answer

Restriction endonuclease

Question 10

Which of the following is a function of lysozyme found in human secretions?

Accepted Answer

Hydrolyzes peptidoglycan in bacterial cell walls

Question 11

Which of the following is a characteristic of endotoxins?

Accepted Answer

Released upon cell lysis

Question 12

Which immune cell is primarily responsible for antibody production?

Accepted Answer

B lymphocyte

Question 13

Which of the following best describes the process of clonal selection in adaptive immunity?

Accepted Answer

Selection and proliferation of lymphocytes specific to an encountered antigen

Question 14

Which of the following is a function of inflammation?

Accepted Answer

Promotes tissue repair and recruits immune cells

Question 15

Which of the following statements about superinfection is correct?

Accepted Answer

It occurs when a new infection arises during treatment for another infection.

Question 16

Which of the following is a direct effect of exotoxins produced by bacteria?

Accepted Answer

Disruption of host cell function

Question 17

Which of the following best explains why broad-spectrum antibiotics can lead to superinfection?

Accepted Answer

They eliminate normal flora, allowing resistant organisms to proliferate.

Question 18

Which of the following is a key difference between sterilization and disinfection?

Accepted Answer

Sterilization removes all forms of microbial life, while disinfection reduces microbial load but may not eliminate all pathogens.

Question 19

Which of the following best describes the function of MHC class I molecules?

Accepted Answer

Present antigens to cytotoxic T cells

Question 20

A patient is exposed to a pathogen and develops immunity after recovering from the infection. What type of immunity is this?

Accepted Answer

Natural active immunity

Microbiology Study Guide: Genetics, Microbial Growth, Antimicrobial Drugs, Infection, and Immunity

Study Guide - Practice Questions