Question 1

Which of the following best describes the term 'antiseptic'?

Accepted Answer

A chemical agent used on living tissue to reduce the number of microorganisms.

Question 2

A hospital wants to ensure that surgical instruments are free of all microbial life, including endospores. Which microbial control term best describes this process?

Accepted Answer

Sterilization

Question 3

Which of the following best explains how high temperatures denature proteins in microorganisms?

Accepted Answer

High temperatures disrupt hydrogen bonds and hydrophobic interactions, causing proteins to lose their tertiary structure.

Question 4

A researcher is testing a new antibiotic. The minimum inhibitory concentration (MIC) is found to be 2 mg/L, while the minimum bactericidal concentration (MBC) is 8 mg/L. What does this indicate about the antibiotic?

Accepted Answer

The antibiotic inhibits growth at 2 mg/L but only kills bacteria at 8 mg/L.

Question 5

If the decimal reduction time ($$D) $$for a bacterial species is 2 minutes, and you start with $$10^6$$ cells, how many cells will remain after 6 minutes of exposure to the killing agent?

Accepted Answer

After each $$D$$, the population is reduced by 90%. After 6 minutes (3 $$D$$), $$10^6$$ 	imes 0.1 	imes 0.1 	imes 0.1 = $$10^3$$ cells remain.

Question 6

Which of the following factors would most likely decrease the efficacy of a disinfectant?

Accepted Answer

Applying the disinfectant to a surface with a large amount of organic matter.

Question 7

Which method is used to evaluate the effectiveness of disinfectants by comparing the ability of a chemical to kill bacteria relative to phenol?

Accepted Answer

Phenol coefficient test

Question 8

Which of the following organisms is most resistant to microbial control methods, and why?

Accepted Answer

Bacterial endospores, because of their tough spore coat and metabolic inactivity.

Question 9

Why might hanging laundry to dry in sunlight be effective at reducing microbial contamination?

Accepted Answer

Sunlight exposes laundry to ultraviolet (UV) radiation, which damages microbial DNA.

Question 10

Which physical control method would be most appropriate for sterilizing heat-sensitive medical equipment?

Accepted Answer

Filtration

Question 11

Which type of heat killing is most effective for sterilizing microbiological media and surgical instruments?

Accepted Answer

Autoclaving

Question 12

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

Accepted Answer

TDT is the shortest time needed to kill all organisms at a given temperature; TDP is the lowest temperature at which all organisms are killed in 10 minutes.

Question 13

Which pasteurization method is most likely to preserve the taste of milk while still reducing microbial load?

Accepted Answer

Batch pasteurization (holding method)

Question 14

A laboratory needs to preserve bacterial cultures for long-term storage. Which method would be most appropriate?

Accepted Answer

Freeze-drying (lyophilization)

Question 15

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

Accepted Answer

Halogens (such as chlorine)

Question 16

A patient with a skin wound needs to prevent infection. Which chemical control is most appropriate?

Accepted Answer

Antiseptic

Question 17

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

Accepted Answer

Alcohols are not effective against bacterial endospores.

Question 18

A food processing plant wants to reduce microbial contamination on surfaces without damaging equipment. Which physical control method is most appropriate?

Accepted Answer

UV radiation

Question 19

Which of the following best describes the use-dilution test for evaluating disinfectants?

Accepted Answer

It determines the minimum concentration of disinfectant required to kill bacteria on metal cylinders.

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

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