Question 1

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

Accepted Answer

Sterilization eliminates all microbial life, including endospores; disinfection removes most pathogens but not endospores.

Question 2

A hospital needs to prepare surgical instruments for use. Which microbial control method is most appropriate?

Accepted Answer

Sterilization

Question 3

Which of the following microbes is the most resistant to physical and chemical control methods?

Accepted Answer

Endospores

Question 4

Why is an autoclave more effective than boiling for sterilization?

Accepted Answer

Autoclaves use higher pressure and temperature, which destroy endospores that boiling cannot.

Question 5

Which chemical agent is most suitable for disinfecting skin before an injection?

Accepted Answer

Alcohol

Question 6

A food processing plant uses high-pressure treatment to preserve fruit. What is the main advantage of this method?

Accepted Answer

It destroys microbes without altering the taste or texture of the fruit.

Question 7

Which of the following is a limitation of using aldehydes as a chemical control method?

Accepted Answer

They are toxic and can damage specimens.

Question 8

A laboratory technician needs to remove bacteria from a solution using filtration. What pore size should the filter have to remove most bacteria?

Accepted Answer

$0.2 \ \mu m$

Question 9

Which physical method is most effective for destroying prions?

Accepted Answer

Incineration

Question 10

Why doesn’t salted fish spoil quickly?

Accepted Answer

Salt creates a hypertonic environment, drawing water out of microbial cells and inhibiting their growth.

Question 11

Which of the following statements about pasteurization is correct?

Accepted Answer

Pasteurization reduces microbial numbers but does not sterilize.

Question 12

A researcher is choosing a disinfectant for a surface contaminated with Pseudomonas. Which limitation should they consider?

Accepted Answer

Pseudomonas is highly resistant to many disinfectants due to its ability to form biofilms.

Question 13

Which of the following is a correct application of the concept of sanitization?

Accepted Answer

Reducing microbial numbers on eating utensils to safe levels.

Question 14

Which chemical agent disrupts cell membranes and is commonly used in disinfectant wipes?

Accepted Answer

Quaternary ammonium compounds (Quats)

Question 15

A food manufacturer wants to reduce spoilage in perishable products. Which method is most effective for slowing microbial growth?

Accepted Answer

Refrigeration

Question 16

Which of the following is a major limitation of using chlorine bleach as a disinfectant?

Accepted Answer

It is corrosive and unstable, making it unsuitable for some surfaces.

Question 17

Which physical method uses moist heat at $121 \ ^\circ C$ and increased pressure to destroy all microbes, including endospores?

Accepted Answer

Autoclaving

Question 18

A scientist is designing a protocol to disinfect a surface contaminated with Mycobacterium. Which chemical agent would be most effective?

Accepted Answer

Aldehydes

Question 19

Which of the following best explains why prions are so difficult to destroy?

Accepted Answer

Prions lack nucleic acids and are resistant to most chemical and physical methods.

Question 20

Which of the following is a real-world example of preservation by reducing water availability?

Accepted Answer

Salting meat to inhibit microbial growth.

Microbial Control: Physical and Chemical Methods

Study Guide - Practice Questions