Q: Which equation best describes the constant percentage of microbial death per unit time, as shown in the microbial death rate plot?

$$N_t = N_0$ \times e$$^{-kt}$$

Question 1

Which of the following terms describes the destruction of all microorganisms and viruses on an object, typically achieved by steam under pressure, incineration, or ethylene oxide gas?

Accepted Answer

Sterilization

Question 2

A hospital is preparing surgical instruments for use. Which method would be most appropriate to ensure sterilization, and what are the standard conditions for this method?

Accepted Answer

Autoclaving at 121ºC, 15 psi, for 15 minutes

Question 3

Which of the following microbes is most resistant to antimicrobial agents, according to the provided susceptibility chart?

Accepted Answer

Prions

Question 4

A disinfectant is tested using the use-dilution test. Which result indicates the most effective agent?

Accepted Answer

Agent prevents growth at highest dilution

Question 5

Which physical method of microbial control is most effective for long-term preservation of microbial cultures and prevents formation of damaging ice crystals?

Accepted Answer

Lyophilization

Question 6

A food manufacturer wants to increase the shelf life of strawberries without using heat. Which method would be most effective?

Accepted Answer

Ionizing radiation

Question 7

Which equation best describes the constant percentage of microbial death per unit time, as shown in the microbial death rate plot?

Accepted Answer

$$N_t = N_0$ 	imes e$$^{-kt}$$

Question 8

Which of the following statements about the efficacy of antimicrobial methods is correct?

Accepted Answer

Intermediate-level germicides kill fungal spores, protozoan cysts, viruses, and pathogenic bacteria

Question 9

Which chemical method is NOT useful for treating open wounds due to the presence of catalase in tissues?

Accepted Answer

Hydrogen peroxide

Question 10

A laboratory technician is working with Ebola virus cultures. Which biosafety level is required for handling such pathogens?

Accepted Answer

Biosafety Level 4 (BSL-4)

Question 11

Which physical method of microbial control is illustrated by drying apricots in the sun, and what is its primary mechanism?

Accepted Answer

Dessication; removal of water inhibits growth

Question 12

Which chemical method is used to prevent blindness caused by Neisseria gonorrhoeae in newborns?

Accepted Answer

1% silver nitrate

Question 13

Which term describes the reduction in the number of microorganisms and viruses, particularly potential pathogens, on living tissue?

Accepted Answer

Antisepsis

Question 14

Which physical method is most appropriate for sterilizing heat-sensitive liquids, such as culture media, without denaturing proteins?

Accepted Answer

Filtration

Question 15

Which chemical method is most effective as a sporicide for sterilizing medical equipment?

Accepted Answer

Peracetic acid

Question 16

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

Accepted Answer

They are often highly explosive and potentially carcinogenic

Question 17

Which method is used to evaluate the efficacy of disinfectants by comparing an agent’s ability to control microbes to phenol, and what does a coefficient greater than 1.0 indicate?

Accepted Answer

Phenol coefficient; agent is more effective than phenol

Question 18

Which physical method of microbial control is most effective for disinfecting air and surfaces, but does not penetrate well?

Accepted Answer

UV light (nonionizing radiation)

Question 19

Which equation describes the relationship between pressure and temperature in an autoclave, as shown in the provided graph?

Accepted Answer

$$P = a 	imes e$$^{bT}$$

Question 20

Which chemical method is commonly used in health care settings, labs, and homes, remains active for prolonged time, but has a disagreeable odor and possible side effects?

Accepted Answer

Phenol and phenolics

Controlling Microbial Growth in the Environment: Principles and Methods

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