Question 1

Which of the following best explains why ionizing radiation is effective at increasing the shelf life of food, as shown in the image of strawberries?

Accepted Answer

It creates ions that disrupt microbial DNA and proteins, killing microbes.

Question 2

Which physical method of microbial control is most suitable for sterilizing heat-sensitive medical equipment?

Accepted Answer

Ionizing radiation (gamma rays)

Question 3

Why are phenolics particularly useful in healthcare settings despite their disagreeable odor?

Accepted Answer

They remain active in the presence of organic matter and persist for a long time.

Question 4

Which of the following statements about nonionizing radiation is correct?

Accepted Answer

It causes pyrimidine dimers in DNA, inhibiting replication.

Question 5

A hospital wants to sterilize a batch of heat-sensitive plastic syringes. Which method should they use?

Accepted Answer

Gaseous agents such as ethylene oxide

Question 6

Which chemical method is most effective for disinfecting surfaces contaminated with bacterial spores?

Accepted Answer

Peracetic acid

Question 7

Why is hydrogen peroxide not always effective for treating open wounds?

Accepted Answer

Catalase in tissues breaks it down into water and oxygen.

Question 8

Which of the following best describes the action of quaternary ammonium compounds (quats)?

Accepted Answer

They disrupt cellular membranes as low-level disinfectants.

Question 9

A laboratory is evaluating a new disinfectant using the use-dilution test. What result indicates the disinfectant is effective?

Accepted Answer

No bacterial growth occurs at the highest dilution tested.

Question 10

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

Accepted Answer

They are often highly explosive and potentially carcinogenic.

Question 11

Which method is most appropriate for disinfecting air in a hospital operating room?

Accepted Answer

UV light

Question 12

Why does denaturation of proteins kill microbial cells?

Accepted Answer

It disrupts the function of essential enzymes and structural proteins.

Question 13

Which of the following is a real-world application of heavy metals in microbial control?

Accepted Answer

Using copper to control algal growth in water reservoirs

Question 14

A disinfectant has a phenol coefficient of 1.5. What does this indicate?

Accepted Answer

It is more effective than phenol.

Question 15

Which enzyme found in human tears is used to reduce bacterial contamination in cheese production?

Accepted Answer

Lysozyme

Question 16

Which of the following best explains why the use of chemical disinfectants can promote the development of resistant microbes?

Accepted Answer

They create selective pressure, allowing resistant strains to survive and multiply.

Question 17

Which chemical method is most appropriate for sterilizing prion-contaminated medical instruments?

Accepted Answer

Prionzyme

Question 18

A solution of 1% silver nitrate is used in newborns' eyes to prevent infection by which organism?

Accepted Answer

Neisseria gonorrhoeae

Question 19

Which of the following is a limitation of using UV light for microbial control?

Accepted Answer

It does not penetrate well, limiting its use to surfaces and air.

Question 20

Which test involves swabbing objects before and after disinfectant application to determine the effectiveness of the disinfectant in real-world conditions?

Accepted Answer

In-use test

Controlling Microbial Growth in the Environment: Physical and Chemical Methods

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