Question 1

Which of the following best explains why ionizing radiation is effective at killing microbes?

Accepted Answer

It ejects electrons from atoms, creating ions that disrupt hydrogen bonding and oxidize double covalent bonds.

Question 2

A hospital wants to sterilize medical equipment using a chemical that is both microbicidal and sporicidal. Which agent would be most appropriate?

Accepted Answer

Peracetic acid

Question 3

Why is UV light not suitable for sterilizing the interior of packaged foods?

Accepted Answer

UV light does not penetrate well, so it cannot reach microbes inside the package.

Question 4

Which chemical method of microbial control is most likely to remain active for a prolonged time, even in the presence of organic matter?

Accepted Answer

Phenol and phenolics

Question 5

A researcher is testing a new disinfectant using the use-dilution test. What result would indicate the disinfectant is highly effective?

Accepted Answer

The disinfectant entirely prevents growth at high dilution.

Question 6

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

Accepted Answer

They are often highly explosive and potentially carcinogenic.

Question 7

Why does denaturation of proteins kill microbial cells?

Accepted Answer

Denatured proteins lose their 3-D structure, preventing them from functioning in essential cellular processes.

Question 8

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

Accepted Answer

They are low-level disinfectants ideal for medical and industrial applications.

Question 9

A food processing plant wants to reduce the number of bacteria in cheese without using heat. Which method would be most appropriate?

Accepted Answer

Treating with lysozyme

Question 10

Which of the following statements about heavy metals is correct?

Accepted Answer

Heavy metals denature proteins and act as low-level bacteriostatic and fungistatic agents.

Question 11

Which method is currently the standard in the United States for evaluating the effectiveness of disinfectants?

Accepted Answer

Use-dilution test

Question 12

A patient is about to receive an injection. Why is the skin swabbed with alcohol beforehand?

Accepted Answer

Alcohol denatures proteins and disrupts cytoplasmic membranes, removing most microbes.

Question 13

Which of the following is a real-world application of halogens in microbial control?

Accepted Answer

Disinfecting water with chlorine treatment

Question 14

Why is hydrogen peroxide not always useful for treating open wounds?

Accepted Answer

It is neutralized by catalase produced by human cells.

Question 15

Which of the following best describes the action of surfactants such as soaps?

Accepted Answer

They reduce surface tension, making them good degerming agents but not antimicrobial.

Question 16

A laboratory is using formalin to disinfect rooms and instruments. What is the mechanism of action?

Accepted Answer

Formalin cross-links functional groups to denature proteins and inactivate nucleic acids.

Question 17

Which of the following is a major concern with the widespread use of antiseptic and disinfectant chemicals?

Accepted Answer

They promote the development of resistant microbes.

Question 18

Which of the following equations best represents the relationship for the phenol coefficient?

Accepted Answer

$PC = \frac{dilution\;of\;test\;agent}{dilution\;of\;phenol}$

Question 19

A medical device is contaminated with prions. Which enzyme would be most effective for removing them?

Accepted Answer

Prionzyme

Question 20

Which of the following is a limitation of using X-rays for microbial control?

Accepted Answer

X-rays penetrate well but require a long time to kill microbes, making them impractical.

Controlling Microbial Growth in the Environment: Physical Methods of Microbial Control

Study Guide - Practice Questions