Question 1

Which of the following organisms is considered to have the highest resistance to microbial control methods?

Accepted Answer

Bacterial endospores

Question 2

A chemical agent that can kill endospores and sterilize surgical instruments is classified as which type of germicide?

Accepted Answer

High-level germicide

Question 3

Which physical method is most appropriate for sterilizing heat-sensitive liquids, such as certain vaccines?

Accepted Answer

Filtration

Question 4

What is the primary mode of action for phenolic compounds as disinfectants?

Accepted Answer

Disrupting lipid membranes

Question 5

Which of the following is NOT a desirable quality for a disinfectant used in a hospital setting?

Accepted Answer

Leaves a toxic residue

Question 6

A solution of ethanol is most effective as a disinfectant at which concentration range?

Accepted Answer

50-70%

Question 7

Which chemical agent is used as a sterilant at high concentrations and as an antiseptic at low concentrations?

Accepted Answer

Hydrogen peroxide ($$H_2O_2)$$

Question 8

Why is irradiation with ionizing radiation (such as x-rays) used for sterilizing medical supplies and foods?

Accepted Answer

It damages DNA and allows low temperature sterilization

Question 9

Which factor does NOT directly affect the death rate of microorganisms during disinfection?

Accepted Answer

Color of the disinfectant

Question 10

Which method is LEAST likely to achieve sterilization?

Accepted Answer

Desiccation

Question 11

A hospital needs to sterilize surgical instruments that cannot be exposed to moisture. Which method should be used?

Accepted Answer

Dry heat oven

Question 12

Which of the following statements about heavy metals as germicides is TRUE?

Accepted Answer

They inactivate enzymes by oligodynamic action

Question 13

Which of the following is a major disadvantage of using chlorine compounds as disinfectants?

Accepted Answer

They are inactivated by organic material

Question 14

A laboratory technician is preparing a bleach solution for surface disinfection. Which property of bleach makes it necessary to prepare fresh solutions frequently?

Accepted Answer

Bleach is unstable in light

Question 15

Which of the following is the correct definition of microbial death?

Accepted Answer

Permanent loss of reproductive capability, even under optimum growth conditions

Question 16

Which of the following is a real-world application of ionizing radiation in food safety?

Accepted Answer

Increasing the shelf life of raspberries by preventing mold growth

Question 17

Which chemical agent is most effective for sterilizing heat-sensitive medical equipment and leaves no toxic residue?

Accepted Answer

Ethylene oxide

Question 18

Which of the following is a limitation of quaternary ammonium compounds (quats) as disinfectants?

Accepted Answer

They are only effective at very low levels

Question 19

A patient is being prepped for surgery with an antiseptic wipe. Which property of alcohol makes it suitable for this purpose?

Accepted Answer

It coagulates proteins in the presence of water

Question 20

Which equation best represents the relationship between the number of viable bacteria ($$N) $$and time ($$t) $$during exposure to a bactericidal agent, assuming exponential death?

Accepted Answer

$$N = N_0$ e$$^{-kt}$$

Control of Microbial Growth: Disinfection, Sterilization, and Methods of Microbial Control

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