Question 1

Which of the following best describes the process of commercial sterilization in the food industry?

Accepted Answer

The destruction of Clostridium botulinum endospores in canned goods.

Question 2

A hospital is deciding between using an autoclave and dry heat sterilization for surgical instruments. Which statement is correct regarding the effectiveness of these methods?

Accepted Answer

Autoclaving at $$121\ ^\circ \mathrm{C}$$ for 15 minutes is preferred because it kills all organisms (except prions) and endospores.

Question 3

Which of the following is the correct definition of decimal reduction time (DRT)?

Accepted Answer

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

Question 4

A solution contains $$1,000,000$$ bacteria. If the decimal reduction time (DRT) is 1 minute, how many bacteria remain after 3 minutes of treatment?

Accepted Answer

$$1,000$$

Question 5

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

Accepted Answer

Filtration using membrane filters with pore sizes as small as $$0.22\ \mu m$$

Question 6

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

Accepted Answer

Their outer membrane contains lipopolysaccharide, which acts as a barrier.

Question 7

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

Accepted Answer

They require water to be effective and are not effective against nonenveloped viruses.

Question 8

A laboratory is testing the effectiveness of a new disinfectant using the use-dilution test. Which result would indicate the disinfectant is effective?

Accepted Answer

No bacterial growth is observed on the cylinders after treatment.

Question 9

Which chemical agent is most effective for sterilizing heat-sensitive medical equipment such as endoscopes?

Accepted Answer

Glutaraldehyde (liquid chemical sterilant)

Question 10

Which of the following best explains why large containers require longer autoclave sterilization times than small containers?

Accepted Answer

It takes longer for the contents of large containers to reach sterilization temperature.

Question 11

Which of the following is a limitation of using nonionizing radiation (UV light) for microbial control?

Accepted Answer

It is only effective on surfaces and does not penetrate well.

Question 12

Which of the following statements about the disk-diffusion method is correct?

Accepted Answer

It evaluates the efficacy of chemical agents by measuring the zone of inhibition around disks.

Question 13

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

Accepted Answer

Silver nitrate – prevention of ophthalmia neonatorum

Question 14

A food processing plant wants to prevent the germination of Clostridium botulinum endospores in meat products. Which additive should they use?

Accepted Answer

Nitrites

Question 15

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

Accepted Answer

It ionizes water to create reactive hydroxyl radicals that damage DNA.

Question 16

Which of the following is NOT a factor that affects the effectiveness of antimicrobial treatments?

Accepted Answer

The color of the disinfectant

Question 17

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

Accepted Answer

They are cationic detergents that denature proteins and disrupt plasma membranes.

Question 18

A patient is treated with a chemical that disrupts plasma membranes. Which of the following is a potential risk of using this chemical on human tissue?

Accepted Answer

It may also damage human cell membranes, leading to toxicity.

Question 19

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

Accepted Answer

It is one of the few liquid chemical sterilizing agents effective against endospores.

Question 20

Which of the following methods is most appropriate for sterilizing tubular surgical instruments that cannot be autoclaved?

Accepted Answer

Plasma sterilization using electrically excited gas

Chapter 7: The Control of Microbial Growth – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards