Question 1

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

Accepted Answer

Sterilization removes all microbial life, including endospores, while disinfection destroys only harmful microorganisms and does not kill endospores.

Question 2

A hospital wants to sterilize heat-sensitive plastic syringes. Which method would be most appropriate?

Accepted Answer

Gaseous chemosterilization with ethylene oxide

Question 3

Which of the following statements about the rate of microbial death is correct?

Accepted Answer

Microbial death occurs at a constant rate and can be plotted as a straight line on a logarithmic scale.

Question 4

A laboratory is testing a new disinfectant using the use-dilution test. Which of the following best describes this method?

Accepted Answer

Metal cylinders are dipped in test bacteria, dried, exposed to disinfectant, and then transferred to culture media to check for survival.

Question 5

Which physical method of microbial control is most effective for sterilizing heat-sensitive solutions such as vaccines?

Accepted Answer

Filtration through membrane filters

Question 6

Which of the following is NOT a factor that affects the effectiveness of antimicrobial treatments?

Accepted Answer

The color of the microbial cells

Question 7

Why is moist heat generally more effective than dry heat for sterilization?

Accepted Answer

Moist heat transfers heat more rapidly and denatures proteins more efficiently.

Question 8

Which of the following statements about alcohol as a disinfectant is TRUE?

Accepted Answer

Alcohol is most effective at a concentration of 70\% because water is required for protein denaturation.

Question 9

A food company wants to prevent the growth of molds in acidic foods such as cheese and soft drinks. Which chemical preservative would be most appropriate?

Accepted Answer

Sorbic acid

Question 10

Which of the following best explains why nonionizing radiation (such as UV light) is not suitable for sterilizing large volumes of liquid?

Accepted Answer

UV light does not penetrate well and requires direct exposure to be effective.

Question 11

Which of the following is a correct application of the term 'asepsis'?

Accepted Answer

Using sterile techniques during surgery to prevent microbial contamination of wounds.

Question 12

A patient with a wound infection is treated with silver nitrate. What is the mechanism of action of this heavy metal?

Accepted Answer

Denaturation of proteins

Question 13

Which of the following statements about quaternary ammonium compounds (quats) is FALSE?

Accepted Answer

Quats are effective against all types of bacteria and endospores.

Question 14

A microbiologist is using an autoclave to sterilize media. What are the standard conditions for autoclaving to achieve sterilization?

Accepted Answer

$$121^{\circ}C$ at 15 psi for 15 minutes

Question 15

Which of the following is the primary reason why endospores are more resistant to chemical disinfectants than vegetative cells?

Accepted Answer

Endospores have tough, protective coats that limit penetration of chemicals.

Question 16

Which of the following chemical agents is most appropriate for disinfecting hospital equipment that cannot withstand high temperatures and is less irritating to living tissue than formaldehyde?

Accepted Answer

Glutaraldehyde

Question 17

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

Accepted Answer

The antiseptic is effective against the tested microbe.

Question 18

Which of the following best describes the action of peroxygens such as hydrogen peroxide on microbial cells?

Accepted Answer

They act as oxidizing agents, disrupting multiple cell components.

Question 19

A restaurant uses a high-temperature dishwasher to clean utensils. Which microbial control term best describes this process?

Accepted Answer

Sanitization

Question 20

Which of the following is a limitation of using halogens such as chlorine for disinfection?

Accepted Answer

They may be inactivated by organic matter.

Chapter 7: The Control of Microbial Growth – Study Notes

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