Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

The removal or destruction of all forms of microbial life, including endospores.

Question 2

A hospital uses an autoclave to sterilize surgical instruments. What are the standard conditions for autoclaving to achieve sterilization?

Accepted Answer

$$121^\circ \mathrm{C} at 15 $$psi for 15 minutes

Question 3

Which of the following terms refers to the mechanical removal of microbes from a limited area, such as cleaning the skin with an alcohol swab before an injection?

Accepted Answer

Degerming

Question 4

A disinfectant is tested using the disk-diffusion method. What does a large zone of inhibition around a disk indicate?

Accepted Answer

The disinfectant is highly effective against the test organism.

Question 5

Which of the following statements about the microbial death curve is correct?

Accepted Answer

Bacterial populations die at a constant rate when plotted logarithmically.

Question 6

Which physical method is most appropriate for sterilizing heat-sensitive solutions such as certain antibiotics?

Accepted Answer

Filtration

Question 7

Which of the following chemical agents is considered a sporicide and can be used for chemical sterilization?

Accepted Answer

Glutaraldehyde

Question 8

Why are gram-negative bacteria generally more resistant to chemical biocides than gram-positive bacteria?

Accepted Answer

They possess an outer membrane that restricts the entry of many biocides.

Question 9

Which of the following best describes the action of ionizing radiation on microbial cells?

Accepted Answer

It damages DNA by causing lethal mutations.

Question 10

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

Accepted Answer

Plasmolysis due to osmotic pressure

Question 11

Which of the following is a correct definition of decimal reduction time ($$D\,R\,T$$)?

Accepted Answer

The time required to kill 90% of a specific population of bacteria at a given temperature.

Question 12

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

Accepted Answer

Alcohols require water to be effective.

Question 13

A nurse cleans a patient’s skin with an iodine solution before surgery. This is an example of:

Accepted Answer

Antisepsis

Question 14

Which of the following is a major advantage of glutaraldehyde over other chemical disinfectants?

Accepted Answer

It is one of the few liquid chemical sterilizing agents.

Question 15

Which of the following best explains why boiling is not always sufficient for sterilization?

Accepted Answer

Boiling does not kill endospores.

Question 16

Which of the following is the primary mechanism by which quaternary ammonium compounds (quats) act as disinfectants?

Accepted Answer

They denature proteins and disrupt plasma membranes.

Question 17

A laboratory technician needs to sterilize a solution that cannot be heated. Which method should be used?

Accepted Answer

Filtration through a $$0.22\,\mu m$$ membrane

Question 18

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

Accepted Answer

It determines the effectiveness of a disinfectant by exposing metal cylinders to bacteria, then to the disinfectant, and finally to growth media.

Question 19

Which of the following statements about pasteurization is correct?

Accepted Answer

High-temperature short-time (HTST) pasteurization uses $$72^\circ \mathrm{C}$$ for 15 seconds.

Question 20

Which of the following is a reason why organic matter can interfere with the effectiveness of a disinfectant?

Accepted Answer

Organic matter can react with and inactivate the disinfectant.

Chapter 7: The Control of Microbial Growth – Comprehensive Study Notes

Study Guide - Practice Questions

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