Question 1

Which of the following best describes the process of disinfection?

Accepted Answer

Destruction of vegetative pathogens, most commonly on inanimate surfaces

Question 2

A hospital is preparing surgical instruments for use. Which method would be most appropriate to ensure sterilization?

Accepted Answer

Hot air sterilization at 121°C for 15 minutes

Question 3

Which of the following is a main action of microbial control agents?

Accepted Answer

Altering membrane permeability

Question 4

A solution of sodium hypochlorite (bleach) is used to disinfect a laboratory bench. Which class of chemical agent does this represent, and what is its primary mode of action?

Accepted Answer

Halogen; disrupts cellular enzymes

Question 5

Which of the following structures, if destroyed, indicates that all other microbial forms are also killed?

Accepted Answer

Endospores

Question 6

A microbiologist is using an autoclave to sterilize media. What is the minimum temperature and time required to kill all organisms, including endospores, using moist heat under pressure?

Accepted Answer

$121^\circ C$ for 15 minutes

Question 7

Which of the following best explains why high concentrations of salts and sugars are used in food preservation?

Accepted Answer

They create hypertonic environments causing plasmolysis

Question 8

A patient is prescribed a mouthwash containing chlorhexidine. What is the primary mechanism by which this biguanide acts?

Accepted Answer

Disrupts cell membranes

Question 9

Which of the following is NOT a physical method of microbial control?

Accepted Answer

Alcohol

Question 10

A laboratory technician uses UV light to disinfect surfaces. Which statement best describes the limitation of this method?

Accepted Answer

UV light has low energy and cannot penetrate surfaces

Question 11

Which of the following factors does NOT directly impact the rate of microbial death when exposed to a chemical agent?

Accepted Answer

Genetic code of the host organism

Question 12

A nurse is instructed to use a quaternary ammonium compound to disinfect a patient’s room. What is the primary action of this compound?

Accepted Answer

Disrupts cell membranes

Question 13

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

Accepted Answer

Antisepsis is the destruction of vegetative pathogens on living tissue, disinfection is on inanimate surfaces

Question 14

A food processing plant uses ionizing radiation to sterilize packaged foods. What is the main advantage of this method over non-ionizing radiation?

Accepted Answer

Ionizing radiation has higher energy and can penetrate packaging and sterilize contents

Question 15

Which of the following is a correct statement about the use of heavy metals as antimicrobial agents?

Accepted Answer

They denature proteins by combining with sulfhydryl groups

Question 16

A microbiologist is testing the effectiveness of a new disinfectant. She finds that the death rate of bacteria exposed to the chemical follows a constant rate. What type of growth or death curve does this represent?

Accepted Answer

Exponential death

Question 17

Which of the following is the most effective method for sterilizing heat-sensitive medical equipment?

Accepted Answer

Ionizing radiation

Question 18

A hospital uses phenol-based cleaners for surfaces. What is the main mechanism by which phenol and its derivatives act as disinfectants?

Accepted Answer

Disrupt cell membranes and denature proteins

Question 19

Which of the following statements about surfactants is correct?

Accepted Answer

Surfactants disrupt cell membranes and remove microbes mechanically

Question 20

A patient with a burn is treated with a cream containing silver sulfadiazine. What is the role of silver in this preparation?

Accepted Answer

Denatures proteins by binding to sulfhydryl groups

Microbial Control: Physical and Chemical Methods

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