Question 1

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization removes all microbial life, while disinfection only destroys harmful microorganisms on nonliving surfaces.

Question 2

A hospital is preparing surgical instruments for use. Which method should be used to ensure all organisms, including endospores (except prions), are destroyed?

Accepted Answer

Autoclaving at 15 psi for 15 minutes

Question 3

Which of the following statements about alcohol-based hand sanitizers is CORRECT?

Accepted Answer

They are not effective against nonenveloped viruses such as Norovirus.

Question 4

A laboratory technician needs to sterilize a heat-sensitive vitamin solution. Which method is most appropriate?

Accepted Answer

Filtration using a membrane filter with 0.2 $$\mum $$pores

Question 5

Which of the following is a reason why biofilms are more resistant to antimicrobial agents than planktonic (free-living) bacteria?

Accepted Answer

Biofilms provide a protective matrix that limits penetration of antimicrobial agents.

Question 6

Which of the following statements about moist heat sterilization is TRUE?

Accepted Answer

It works primarily by coagulating proteins.

Question 7

A food processing plant uses high concentrations of salt to preserve meat. What is the primary mechanism by which this inhibits microbial growth?

Accepted Answer

Osmotic pressure causes plasmolysis of microbial cells.

Question 8

Which of the following chemical agents is correctly matched with its mechanism of action?

Accepted Answer

Chlorine compounds act as oxidizing agents.

Question 9

A researcher is evaluating a new disinfectant using the disk-diffusion method. What is being measured in this test?

Accepted Answer

The zone of inhibition around the disk

Question 10

Which of the following statements about aldehydes is CORRECT?

Accepted Answer

They inactivate proteins by cross-linking functional groups.

Question 11

A hospital uses ethylene oxide to sterilize heat-sensitive medical equipment. Which of the following is a critical requirement for this process?

Accepted Answer

The equipment must be placed in a sealed chamber.

Question 12

Which of the following best explains why organic matter can interfere with the effectiveness of disinfectants?

Accepted Answer

Organic matter can react with and inactivate disinfectant chemicals.

Question 13

Which of the following is a TRUE statement about the use-dilution test?

Accepted Answer

It is the current standard for evaluating disinfectant effectiveness.

Question 14

Which of the following is a correct pairing of a chemical agent and its common use?

Accepted Answer

Silver nitrate is used to prevent ophthalmia neonatorum.

Question 15

A microbiologist is using ultraviolet (UV) light to disinfect a laboratory bench. What is the primary mechanism by which UV light kills microbes?

Accepted Answer

It causes thymine dimers in DNA.

Question 16

Which of the following statements about pasteurization is TRUE?

Accepted Answer

HTST pasteurization heats liquids to 70$$^\circC $$for 15 seconds.

Question 17

Which of the following is a property of phenolics that makes them useful in disinfectants like Lysol?

Accepted Answer

They remain active in the presence of organic matter.

Question 18

A scientist is comparing the effectiveness of two disinfectants at different concentrations and temperatures. Which principle is being evaluated?

Accepted Answer

Principles of effective disinfection

Question 19

Which of the following statements about peroxygens is CORRECT?

Accepted Answer

Hydrogen peroxide is a good disinfectant for nonliving surfaces.

Question 20

A nurse is preparing a tincture of iodine for skin antisepsis. What is a tincture?

Accepted Answer

A solution of iodine in aqueous alcohol

Microbial Control: Methods and Principles (Chapter 7 Study Notes)

Study Guide - Practice Questions

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