Question 1

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization destroys all forms of microbial life, including endospores and prions, while disinfection destroys only vegetative microbes and does not affect endospores.

Question 2

A hospital needs to sterilize heat-sensitive plastic instruments. Which method is most appropriate?

Accepted Answer

Ethylene oxide gas sterilization

Question 3

Which of the following organisms is most resistant to antimicrobial treatment?

Accepted Answer

Prions

Question 4

A food processing plant wants to reduce the risk of Clostridium botulinum contamination in canned foods. Which process should they use?

Accepted Answer

Commercial sterilization

Question 5

Which physical method is most effective for sterilizing glassware in a laboratory?

Accepted Answer

Autoclaving at 121ºC and 15 psi for 20 minutes

Question 6

Which of the following statements about pasteurization is correct?

Accepted Answer

Pasteurization reduces the number of viable pathogens but does not sterilize the product.

Question 7

A laboratory technician needs to sterilize a heat-sensitive vitamin solution. Which method should be used?

Accepted Answer

Filtration through a 0.22 μm membrane filter

Question 8

Which chemical agent is most effective in the presence of organic matter such as vomit or feces?

Accepted Answer

Phenolics

Question 9

Which of the following best explains why refrigeration is considered a microbiostatic method?

Accepted Answer

It inhibits the growth of most pathogens without killing them.

Question 10

A researcher is using the disk-diffusion method to evaluate a new disinfectant. What does a large zone of inhibition around the disk indicate?

Accepted Answer

The disinfectant is effective against the test organism.

Question 11

Which of the following is a disadvantage of using ethylene oxide gas for sterilization?

Accepted Answer

It is toxic and potentially explosive.

Question 12

Which of the following best describes the decimal reduction time (DRT)?

Accepted Answer

The time in minutes required to kill 90% of a microbial population at a given temperature.

Question 13

Which of the following statements about ionizing radiation is correct?

Accepted Answer

It causes DNA damage and can sterilize medical supplies.

Question 14

Which of the following is a real-world example of degermination?

Accepted Answer

Cleaning the skin with alcohol before an injection

Question 15

A food manufacturer wants to store fruit juice at room temperature for several months without spoilage. Which method should be used?

Accepted Answer

Ultra-high temperature (UHT) pasteurization

Question 16

Which of the following is a limitation of using high concentrations of heavy metals for microbial control?

Accepted Answer

They can be toxic to humans and the environment.

Question 17

Which of the following best explains why molds are more resistant to high osmotic pressure than bacteria?

Accepted Answer

Molds can grow in hypertonic environments due to their cell wall structure.

Question 18

A nurse is preparing a patient’s skin for surgery. Which term best describes the process of using an iodine solution on the skin?

Accepted Answer

Antisepsis

Question 19

Which of the following is a disadvantage of using phenol as a disinfectant in medical settings?

Accepted Answer

It can irritate skin and mucous membranes.

Question 20

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

Accepted Answer

It inhibits microbial growth by removing water, but some microbes can survive.

Physical and Chemical Methods of Microbial Control

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