Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

The removal or destruction of all forms of microbial life.

Question 2

A hospital uses an autoclave to sterilize surgical instruments. Which combination of temperature and time is most commonly used in autoclaving to ensure sterilization?

Accepted Answer

$$121^\circ C$$ for 15 minutes

Question 3

Which microbial structure is most resistant to chemical and physical methods of control?

Accepted Answer

Endospores of bacteria

Question 4

A laboratory technician uses a membrane filter with a pore size of $$0.22\ \mu m to $$sterilize a solution. Which of the following will most likely pass through the filter?

Accepted Answer

Viruses

Question 5

Which of the following statements about pasteurization is correct?

Accepted Answer

It reduces spoilage organisms and pathogens by heating materials for a short time.

Question 6

Which physical method of microbial control damages DNA by creating thymine dimers?

Accepted Answer

Nonionizing radiation (ultraviolet)

Question 7

A solution of 70% ethanol is used as a disinfectant. What is the primary mechanism by which ethanol kills microbes?

Accepted Answer

Denatures proteins and dissolves lipids

Question 8

Which of the following is NOT effectively killed by quaternary ammonium compounds?

Accepted Answer

Endospores

Question 9

A microbiologist is using direct flaming to sterilize an inoculating loop. Which type of heat is being applied?

Accepted Answer

Dry heat

Question 10

Which of the following best explains why prions are difficult to destroy using standard sterilization techniques?

Accepted Answer

They lack nucleic acids and are resistant to denaturation.

Question 11

A food processing plant uses high-efficiency particulate air (HEPA) filters. What is the minimum particle size that HEPA filters are designed to remove?

Accepted Answer

$$0.3\ \mu m$$

Question 12

Which of the following chemical agents is most effective against endospores?

Accepted Answer

Hydrogen peroxide (25%)

Question 13

A patient with a wound is treated with an agent that destroys vegetative pathogens on living tissue. This process is called:

Accepted Answer

Antisepsis

Question 14

Which of the following best describes the effect of bacteriostatic agents?

Accepted Answer

They inhibit the growth of bacteria without killing them.

Question 15

A solution is treated with osmotic pressure to control microbial growth. Which of the following best describes the mechanism?

Accepted Answer

Removal of water from cells, leading to plasmolysis

Question 16

Which of the following is a real-life application of degerming?

Accepted Answer

Washing hands with soap before surgery

Question 17

A researcher exposes a bacterial culture to UV light at 260 nm. What is the most likely effect on the bacteria?

Accepted Answer

Formation of thymine dimers in DNA

Question 18

Which of the following best explains why moist heat is generally more effective than dry heat for sterilization?

Accepted Answer

Moist heat denatures proteins more rapidly due to better heat penetration.

Question 19

A solution is filtered through a membrane with a pore size of $$0.22\ \mu m. $$Which of the following organisms will most likely be retained by the filter?

Accepted Answer

Most bacteria

Question 20

A nurse wipes a patient's skin with an alcohol swab before an injection. This is an example of:

Accepted Answer

Degerming

Control of Microbial Growth: Principles and Methods

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