Question 1

Which of the following characteristics is NOT ideal for an agent used to control microbial growth in a hospital setting?

Accepted Answer

It is expensive and difficult to store.

Question 2

A surgical instrument contaminated with prions requires which level of germicide for proper decontamination?

Accepted Answer

High-level germicide

Question 3

Why is autoclaving more effective than boiling for sterilization?

Accepted Answer

Autoclaving uses increased pressure to raise the boiling point of water, allowing higher temperatures that destroy endospores and prions.

Question 4

Which of the following microbes is MOST resistant to antimicrobial agents?

Accepted Answer

Prions

Question 5

A laboratory technician is working with a microbe that causes severe or fatal disease. Which biosafety level (BSL) is required?

Accepted Answer

BSL-4

Question 6

Which environmental condition can decrease the efficacy of a chemical disinfectant when cleaning a surface contaminated with organic matter?

Accepted Answer

Presence of organic materials

Question 7

Which of the following statements about moist heat sterilization is TRUE?

Accepted Answer

Moist heat denatures proteins and destroys cytoplasmic membranes more effectively than dry heat.

Question 8

A batch of milk is pasteurized using the batch method. What temperature and time are required for this process?

Accepted Answer

$$63\ ^\circ\mathrm{C}$$ for 30 minutes

Question 9

Which physical method of microbial control is most appropriate for sterilizing heat-sensitive liquids such as vaccines?

Accepted Answer

Filtration

Question 10

A food manufacturer wants to preserve apricots for long-term storage without refrigeration. Which method should be used?

Accepted Answer

Desiccation

Question 11

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

Accepted Answer

Slow freezing allows ice crystals to form, which damage microbial cell structures.

Question 12

A solution contains $$10^6$$ bacteria. If the decimal reduction time ($$D) is 2 $$minutes, how many bacteria remain after 6 minutes of treatment?

Accepted Answer

$$10^3$$

Question 13

Which of the following is the ultimate means of sterilization for materials that cannot be treated with moist heat?

Accepted Answer

Incineration

Question 14

Why are BSL-4 suits pressurized?

Accepted Answer

To prevent pathogens from entering the suit in case of a breach.

Question 15

Which of the following is LEAST likely to be killed by boiling water for 10 minutes?

Accepted Answer

Bacterial endospores

Question 16

A hospital is using HEPA filters in its safety cabinets. What is the primary purpose of these filters?

Accepted Answer

To remove airborne microbes and particles from the air.

Question 17

Which method is used to prevent the formation of damaging ice crystals during long-term preservation of microbial cultures?

Accepted Answer

Lyophilization (freeze-drying)

Question 18

Which of the following statements about osmotic pressure is correct?

Accepted Answer

High concentrations of salt or sugar inhibit microbial growth by causing cells to lose water.

Question 19

Which of the following is TRUE regarding the effect of temperature on the efficacy of antimicrobial chemicals?

Accepted Answer

Higher temperatures generally increase the rate of microbial death.

Question 20

A nurse is cleaning a wound with a low-level germicide. Which types of microbes will be reliably killed by this treatment?

Accepted Answer

Vegetative bacteria, fungi, protozoa, and some viruses

Controlling Microbial Growth in the Environment: Principles and Methods

Study Guide - Practice Questions