Question 1

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

Accepted Answer

Sterilization removes all forms of microbial life, including spores, while disinfection only reduces the number of pathogenic organisms.

Question 2

Which physical method of microbial control is most effective at destroying nucleic acids and proteins by causing molecular vibrations?

Accepted Answer

Ionizing radiation

Question 3

A hospital uses autoclaving to sterilize surgical instruments. If the autoclave operates at 121°C and 15 psi for 15 minutes, which microbial component is most likely to be destroyed first?

Accepted Answer

Proteins

Question 4

Which of the following is NOT a factor that influences the effectiveness of antimicrobial agents?

Accepted Answer

The color of the microbial colony

Question 5

Which of the following best explains why Gram-negative bacteria are generally more resistant to antimicrobial agents than Gram-positive bacteria?

Accepted Answer

They possess an outer membrane that restricts entry of many chemicals.

Question 6

Which chemical agent is most likely to be used for sterilizing heat-sensitive medical equipment?

Accepted Answer

Ethylene oxide gas

Question 7

A laboratory technician wants to calculate the time required to reduce a microbial population from $$10^6 to$$ $$10^2$$ cells using a chemical agent with a D-value of 2 minutes. What is the total time required?

Accepted Answer

$$8$$ minutes

Question 8

Which of the following is a correct description of how hypertonic solutions limit microbial growth?

Accepted Answer

They cause water to leave the microbial cell, leading to plasmolysis.

Question 9

Which of the following is a major advantage of using nonionizing radiation (such as UV light) for microbial control?

Accepted Answer

It damages DNA by causing thymine dimers, preventing replication.

Question 10

Which of the following is a limitation of using freezing as a method of microbial control?

Accepted Answer

Freezing is less damaging to microbes than slow freezing, allowing some to survive.

Question 11

Which of the following best describes how lysozyme works as an antimicrobial agent?

Accepted Answer

It hydrolyzes the bonds in peptidoglycan, weakening bacterial cell walls.

Question 12

Which of the following is an example of a biosafety level 4 (BSL-4) laboratory practice?

Accepted Answer

Working with Ebola virus in a full-body, air-supplied suit.

Question 13

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

Accepted Answer

Aldehydes

Question 14

A food processing plant uses pasteurization to control microbial growth in milk. Which statement best describes pasteurization?

Accepted Answer

It reduces the number of pathogenic microbes without sterilizing the product.

Question 15

Which of the following is a reason why some microbes are resistant to chemical disinfectants?

Accepted Answer

They form biofilms that protect them from exposure.

Question 16

Which of the following is a correct comparison between moist heat and dry heat methods of microbial control?

Accepted Answer

Moist heat is generally more effective at lower temperatures than dry heat.

Question 17

Which of the following is a correct statement about the use of filtration for microbial control?

Accepted Answer

Filtration physically removes microbes from liquids and air without killing them.

Question 18

A researcher is testing the effect of a new antimicrobial agent on a mixed culture containing both Gram-positive and Gram-negative bacteria. Which factor is most likely to influence the agent's effectiveness?

Accepted Answer

The composition of the bacterial cell wall

Question 19

Which of the following is a correct description of how aldehydes act as antimicrobial agents?

Accepted Answer

They cross-link proteins and nucleic acids, inactivating microbial cells.

Question 20

A scientist exposes a bacterial culture to UV light for 10 minutes. Which of the following outcomes is most likely?

Accepted Answer

The bacteria will develop thymine dimers in their DNA, inhibiting replication.

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