Question 1

Which biosafety level (BSL) is required for handling microbes that are dangerous and exotic, pose a high risk of aerosol-transmitted infections, and often lack available treatments or vaccines?

Accepted Answer

BSL-4

Question 2

Which of the following best describes sterilization?

Accepted Answer

A process that destroys all viable microbes, including viruses and endospores

Question 3

A laboratory technician is using an autoclave to sterilize surgical instruments. What is the primary advantage of using moist heat (autoclaving) over dry heat sterilization?

Accepted Answer

Moist heat penetrates cells better, allowing for complete sterilization at lower temperatures and shorter times

Question 4

Which of the following statements about pasteurization is correct?

Accepted Answer

HTST pasteurization exposes milk to 72 \degree C for 15 seconds

Question 5

A food manufacturer wants to preserve jerky using desiccation. What is the main reason this method inhibits microbial growth?

Accepted Answer

It removes water, halting microbial metabolism

Question 6

Which of the following is a correct equation for the catalase reaction that detoxifies hydrogen peroxide?

Accepted Answer

$$2H_2O_2 \xrightarrow{catalase} 2H_2O + O_2$

Question 7

A hospital uses HEPA filters in its ventilation system. What is the primary function of these filters?

Accepted Answer

To physically remove microbes, endospores, and viruses from the air

Question 8

Which of the following agents is most appropriate for sterilizing heat-sensitive medical instruments?

Accepted Answer

Glutaraldehyde (2% solution)

Question 9

Why are heavy metals such as silver and copper effective as antimicrobial agents?

Accepted Answer

They bind to proteins, inhibiting enzymatic activity

Question 10

A microbiologist is testing the effectiveness of several disinfectants using the disk-diffusion method. What does a larger zone of inhibition around a disk indicate?

Accepted Answer

The disinfectant is more effective at inhibiting microbial growth

Question 11

Which of the following best explains why UV radiation is used to control microbial growth on surfaces?

Accepted Answer

It causes the formation of thymine dimers in DNA, leading to lethal mutations

Question 12

Which of the following is NOT a factor that affects microbial death rate during disinfection?

Accepted Answer

Color of the microbe

Question 13

Which of the following statements about alcohols as disinfectants is correct?

Accepted Answer

Alcohols work by rapidly denaturing proteins and disrupting membranes

Question 14

A patient is about to undergo surgery. Which chemical agent is most likely used as a topical antiseptic on the skin before incision?

Accepted Answer

Betadine (iodine solution)

Question 15

Which of the following best describes the action of surfactants such as soaps?

Accepted Answer

They emulsify lipids, allowing mechanical removal of microbes

Question 16

Which of the following is the correct definition of thermal death time (TDT)?

Accepted Answer

The shortest length of time required to kill all test microbes at a specified temperature

Question 17

Which of the following is a practical concern when selecting a method for microbial control in a hospital setting?

Accepted Answer

Whether the item can withstand heat, pressure, radiation, or chemicals

Question 18

Which of the following is true regarding the use of refrigeration for microbial control?

Accepted Answer

Refrigeration inhibits microbial metabolism, making it microbiostatic

Question 19

Which of the following statements about phenolic compounds is correct?

Accepted Answer

Phenolics disrupt cell walls and membranes and precipitate proteins

Question 20

Which of the following best describes the effect of adding salt or sugar to foods as a preservation method?

Accepted Answer

It creates a hypertonic environment, drawing water out of microbial cells

Control of Microbial Growth: Methods and Applications

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