Q: Which equation best represents the decimal reduction time (DRT) for a bacterial population, where $$N_0 is $$the initial number of cells and $$N is $$the number remaining after time $$t$$?

$$N = N_0$ \times 0.1$$^{t/DRT}$$

Question 1

Which term describes the process of removing and destroying all microbial life, including endospores, from an object?

Accepted Answer

Sterilization

Question 2

A hospital uses an autoclave to sterilize surgical instruments. If a 9000-mL bottle requires 70 minutes to sterilize, but a 500-mL flask only requires 5 minutes, what is the primary reason for this difference?

Accepted Answer

The larger bottle takes longer to reach sterilization temperature

Question 3

Which physical method of microbial control is most effective for sterilizing heat-sensitive solutions, such as vaccines?

Accepted Answer

Filtration

Question 4

A chemical agent damages the plasma membrane of bacteria. Which of the following is a likely consequence?

Accepted Answer

Leakage of cellular contents

Question 5

Which equation best represents the decimal reduction time (DRT) for a bacterial population, where $$N_0 is $$the initial number of cells and $$N is $$the number remaining after time $$t$$?

Accepted Answer

$$N = N_0$ 	imes 0.1$$^{t/DRT}$$

Question 6

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

Accepted Answer

They possess lipopolysaccharide in their outer membrane

Question 7

Which chemical method is most effective for skin antisepsis before surgery?

Accepted Answer

Chlorhexidine

Question 8

A food manufacturer wants to prevent Clostridium botulinum endospore germination in canned meats. Which preservative should be used?

Accepted Answer

Nitrites

Question 9

Which type of radiation is most effective for sterilizing pharmaceuticals and disposable medical supplies due to its deep penetration and ability to cause lethal mutations?

Accepted Answer

Ionizing radiation (gamma rays)

Question 10

A laboratory technician uses the disk-diffusion method to test disinfectants. What does a large zone of inhibition around a disk indicate?

Accepted Answer

The disinfectant is highly effective against the test organism

Question 11

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

Accepted Answer

They require water to be effective

Question 12

Which method is used to sterilize items that cannot withstand high temperatures or moisture, such as medical implants?

Accepted Answer

Supercritical fluids

Question 13

Which of the following is NOT a practical exception to the definition of sterilization?

Accepted Answer

Sterilization of prions

Question 14

Which chemical disinfectant can be considered a sporicide?

Accepted Answer

Chlorine

Question 15

Which of the following best describes the effect of desiccation on microbial cells?

Accepted Answer

It prevents metabolism by removing water

Question 16

A dairy industry manager is choosing a surface-active agent for cleaning equipment. Which characteristic is most attractive for this application?

Accepted Answer

Ability to dissolve lipids and remove organic matter

Question 17

Which of the following is true about the effectiveness of moist heat versus dry heat for microbial control?

Accepted Answer

Moist heat is more effective than dry heat at the same temperature

Question 18

Which equation describes the logarithmic decrease in microbial population during sterilization, where $$N_0 is $$the initial population, $$N is $$the surviving population, and $$k is $$the rate constant?

Accepted Answer

$$\log_{10} N = \log_{10} N_0$ - kt$$

Question 19

Which of the following is a limitation of using alcohols as disinfectants?

Accepted Answer

They are not effective against nonenveloped viruses

Question 20

A patient is treated with Betadine® before surgery. What is the role of Betadine® in this scenario?

Accepted Answer

Antiseptic

Chapter 7: The Control of Microbial Growth – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards