Question 1

Which chemical method of microbial control is most appropriate for disinfecting heat-sensitive hospital mattresses?

Accepted Answer

Ethylene oxide gas

Question 2

What is the primary mode of action for phenolic compounds such as Triclosan and Lysol?

Accepted Answer

Damage proteins and membranes

Question 3

Why is 100% ethanol less effective as a disinfectant than 62-65% ethanol?

Accepted Answer

Water is required for protein denaturation, which is optimal at 62-65% ethanol

Question 4

Which chemical agent is commonly used for skin and wound treatment due to its ability to damage proteins?

Accepted Answer

Iodine

Question 5

Arrange the following microbes in order of resistance to antimicrobial agents, from most to least: Gram-negative bacteria, prions, bacterial endospores, Gram-positive bacteria.

Accepted Answer

Prions > Bacterial endospores > Gram-negative bacteria > Gram-positive bacteria

Question 6

A hospital needs to disinfect surgical instruments that cannot be exposed to high temperatures. Which chemical method should be used?

Accepted Answer

Ethylene oxide gas

Question 7

Which chemical agent is used for disinfecting medical equipment and embalming, and what is its mode of action?

Accepted Answer

Glutaraldehyde; damages proteins and nucleic acids

Question 8

What is the main reason Gram-negative bacteria are more resistant to antimicrobial agents than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane that limits agent penetration

Question 9

Which of the following is a correct application of chlorine as a chemical method of microbial control?

Accepted Answer

Treating drinking water and swimming pools

Question 10

A researcher is testing the effectiveness of different ethanol concentrations on bacterial growth. According to the study materials, which concentration is most effective and why?

Accepted Answer

62-65% ethanol, because water is required for optimal protein denaturation

Question 11

Which chemical method of microbial control is most likely to be used in antibacterial soaps?

Accepted Answer

Triclosan (a phenolic)

Question 12

Which chemical agent damages both proteins and nucleic acids and is used for sterilizing heat-sensitive materials?

Accepted Answer

Ethylene oxide gas

Question 13

A patient’s wound is being treated with Betadine. Which chemical group does Betadine belong to and what is its mode of action?

Accepted Answer

Halogens; damages proteins

Question 14

Which of the following best explains why bacterial endospores are highly resistant to chemical disinfectants?

Accepted Answer

They possess a tough, protective coat and low metabolic activity

Question 15

Which chemical method is least likely to be effective against prions?

Accepted Answer

Ethylene oxide gas

Question 16

A laboratory technician needs to disinfect a surface contaminated with Gram-negative bacteria. Which chemical method would be most effective, considering the bacteria’s resistance?

Accepted Answer

Alcohols at 62-65% concentration

Question 17

Which chemical agent is most appropriate for disinfecting medical equipment prior to surgery, and what is its mechanism?

Accepted Answer

Glutaraldehyde; damages proteins and nucleic acids

Question 18

Which chemical method of microbial control is most likely to be used in wastewater treatment plants?

Accepted Answer

Chlorine

Question 19

Which of the following equations best represents the relationship between concentration of ethanol and microbial growth inhibition, based on the study materials?

Accepted Answer

$NG = f(C_{ethanol}, t_{exposure})$

Question 20

Which chemical agent is most likely to be used for embalming, and what is its primary target in microbial cells?

Accepted Answer

Glutaraldehyde; proteins and nucleic acids

Chemical Methods for Controlling Microbial Growth in the Environment

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