Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

The removal and destruction of all microbial life

Question 2

A hospital is preparing surgical instruments for use. Which method would be most appropriate to ensure all organisms, including endospores (but not prions), are destroyed?

Accepted Answer

Autoclaving at 15 psi for 15 minutes

Question 3

Which of the following statements about alcohols as disinfectants is correct?

Accepted Answer

Alcohols denature proteins and dissolve lipids

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 with 0.2 \mu m pores

Question 5

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

Accepted Answer

It is the current standard for evaluating disinfectants

Question 6

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

Accepted Answer

Creation of a hypertonic environment causing plasmolysis

Question 7

Which of the following statements about phenolics is true?

Accepted Answer

Phenolics damage the plasma membrane

Question 8

A nurse is preparing to scrub in for surgery. Which chemical agent is most likely used for surgical hand scrubs?

Accepted Answer

Chlorhexidine

Question 9

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

Accepted Answer

Biofilms protect microbes by creating a physical barrier to agents

Question 10

Which of the following statements about ionizing radiation is correct?

Accepted Answer

Ionizing radiation creates reactive hydroxyl radicals

Question 11

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

Accepted Answer

The zone of inhibition around the chemical agent

Question 12

Which of the following is a property of aldehydes as chemical control agents?

Accepted Answer

They inactivate proteins by cross-linking functional groups

Question 13

A researcher is using a hot-air oven at 160 \degree C for 2 hours to sterilize glassware. What is the primary mechanism by which this method kills microbes?

Accepted Answer

Oxidation of cellular components

Question 14

Which of the following statements about pasteurization is correct?

Accepted Answer

HTST pasteurization heats liquids to 70 \degree C for 15 seconds

Question 15

A hospital is considering the use of ethylene oxide for sterilizing heat-sensitive medical equipment. Which of the following is a correct statement about ethylene oxide?

Accepted Answer

It must be used in a sealed chamber to be effective

Question 16

Which of the following best describes the action of chlorine compounds such as bleach?

Accepted Answer

They act as oxidizing agents

Question 17

A patient is treated with silver nitrate to prevent ophthalmia neonatorum. What is the mechanism of action of silver nitrate?

Accepted Answer

It denatures proteins via oligodynamic action

Question 18

Which of the following is a correct statement about peroxygens?

Accepted Answer

Hydrogen peroxide is a good disinfectant for nonliving surfaces

Question 19

A scientist is evaluating the effectiveness of a new disinfectant. Which factors should be considered to ensure accurate results? Select the best answer.

Accepted Answer

Concentration, presence of organic matter, temperature, and exposure time

Question 20

A microbiologist is using ultraviolet (UV) radiation to disinfect a laboratory surface. What is the primary effect of UV radiation on microbial DNA?

Accepted Answer

It causes the formation of thymine dimers

Control of Microbial Growth: Principles and Methods

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