Question 1

Which of the following best describes an antiseptic?

Accepted Answer

A chemical used to inhibit or destroy microorganisms on living tissue.

Question 2

How do high temperatures generally affect microbial proteins?

Accepted Answer

They denature proteins, leading to loss of function.

Question 3

Which scenario best illustrates the use of a disinfectant?

Accepted Answer

Wiping a kitchen counter with bleach solution.

Question 4

What is the main difference between minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)?

Accepted Answer

MIC is the lowest concentration that inhibits visible growth; MBC is the lowest that kills 99.9% of bacteria.

Question 5

If a bacterial population is reduced from $$10^6 to$$ $$10^3$$ cells after 3 minutes of treatment, what is the decimal reduction time (D-value)?

Accepted Answer

$$1$$ minute

Question 6

Which of the following is NOT a factor that affects the efficacy of antimicrobial methods?

Accepted Answer

Color of the disinfectant

Question 7

Which method is commonly used to evaluate the effectiveness of disinfectants and antiseptics?

Accepted Answer

Disk-diffusion method

Question 8

Which of the following organisms is generally the most resistant to control methods?

Accepted Answer

Bacterial endospores

Question 9

Why might hanging laundry to dry in sunlight reduce microbial contamination?

Accepted Answer

Ultraviolet (UV) radiation in sunlight damages microbial DNA.

Question 10

Which type of heat killing is most appropriate for sterilizing heat-sensitive liquids?

Accepted Answer

Pasteurization

Question 11

What is the difference between thermal death time (TDT) and thermal death point (TDP)?

Accepted Answer

TDT is the shortest time to kill all microbes at a set temperature; TDP is the lowest temperature to kill all microbes in a set time.

Question 12

Which pasteurization method uses the highest temperature for the shortest time?

Accepted Answer

Ultra-high temperature (UHT) pasteurization

Question 13

Which physical control method would be most appropriate for preserving bacterial cultures for long-term storage?

Accepted Answer

Freeze-drying (lyophilization)

Question 14

Which chemical control would you use to ensure drinking water is free of pathogens?

Accepted Answer

Chlorine

Question 15

A hospital needs to sterilize heat-sensitive plastic syringes. Which method should be used?

Accepted Answer

Ethylene oxide gas

Question 16

If the decimal reduction time ($$D) $$for a microbe at $$121^{\circ}C$ is 2$ minutes, how many minutes are required to reduce a population from 10^7$ to 10^1$ cells?

Accepted Answer

$$14$$ minutes

Question 17

Which of the following best explains why bacterial endospores are highly resistant to control methods?

Accepted Answer

They have a thick protein coat and low metabolic activity.

Question 18

Which chemical control is most appropriate for skin antisepsis before an injection?

Accepted Answer

Alcohol (e.g., isopropanol)

Question 19

Which of the following is a limitation of using refrigeration as a microbial control method?

Accepted Answer

It only slows microbial growth but does not kill most microbes.

Question 20

A laboratory is testing a new disinfectant. Which method would best determine its effectiveness against Staphylococcus aureus?

Accepted Answer

Measuring the zone of inhibition in a disk-diffusion assay

Microbial Control: Methods, Terms, and Applications (Chapter 9 Study Guide)

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