Question 1

Which of the following best describes the mechanism by which moist heat kills microorganisms?

Accepted Answer

It denatures proteins and destroys cytoplasmic membranes.

Question 2

A hospital is deciding between using phenol and a new disinfectant. The phenol coefficient of the new disinfectant is 1.5. What does this indicate?

Accepted Answer

The new disinfectant is more effective than phenol.

Question 3

Which of the following organisms is most resistant to antimicrobial agents, according to the susceptibility chart?

Accepted Answer

Prions

Question 4

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

Accepted Answer

Filtration through a membrane filter

Question 5

Which of the following statements about pasteurization is correct?

Accepted Answer

It reduces the number of spoilage organisms and pathogens in milk.

Question 6

A solution is treated with a chemical that cross-links functional groups in proteins and nucleic acids. Which class of chemical agent is being used?

Accepted Answer

Aldehydes

Question 7

Which of the following best explains why slow freezing is more effective than quick freezing for microbial control?

Accepted Answer

Slow freezing causes more ice crystals to form, which puncture cell membranes.

Question 8

A disinfectant is tested using the use-dilution test. What result indicates the disinfectant is most effective?

Accepted Answer

It prevents growth at the highest dilution tested.

Question 9

Which of the following is a limitation of using hydrogen peroxide as an antiseptic for open wounds?

Accepted Answer

It is inactivated by catalase present in tissues.

Question 10

Which of the following best describes the decimal reduction time (D-value) in microbial control?

Accepted Answer

The time required to reduce a microbial population by 90%.

Question 11

A food processing plant wants to extend the shelf life of strawberries without using heat. Which method is most appropriate?

Accepted Answer

Irradiation with gamma rays

Question 12

Which of the following is a disadvantage of using gaseous agents for sterilization?

Accepted Answer

They are often highly explosive and potentially carcinogenic.

Question 13

Which of the following best explains why nonenveloped viruses are more resistant to harsh conditions than enveloped viruses?

Accepted Answer

They have a thicker protein coat that resists chemical attack.

Question 14

A laboratory is classified as Biosafety Level 4 (BSL-4). Which of the following is most likely being handled in this lab?

Accepted Answer

Ebola virus

Question 15

Which of the following statements about quaternary ammonium compounds (quats) is correct?

Accepted Answer

They are low-level disinfectants ideal for many medical applications.

Question 16

Which of the following is the primary reason why high concentrations of salt or sugar are used to preserve foods?

Accepted Answer

They create a hypertonic environment, causing cells to lose water.

Question 17

Which of the following is a real-world example of degerming?

Accepted Answer

Washing hands with soap and water

Question 18

Which of the following best describes the action of UV light as a microbial control method?

Accepted Answer

It causes the formation of pyrimidine dimers in DNA.

Question 19

A patient is prescribed a topical ointment containing 1% silver nitrate. What is the primary antimicrobial mechanism of this compound?

Accepted Answer

It denatures proteins by interacting with sulfhydryl groups.

Question 20

Which of the following is a potential consequence of widespread use of antiseptic and disinfectant chemicals?

Accepted Answer

Development of resistant microbes

Microbial Control: Principles, Methods, and Applications

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