Question 1

Which of the following best describes microbial death?

Accepted Answer

A permanent loss of reproductive ability under ideal environmental conditions

Question 2

A hospital is sterilizing surgical instruments using an autoclave. What are the standard conditions required for effective autoclaving?

Accepted Answer

$$121^\circ \mathrm{C}$$, 15 psi, 15 minutes

Question 3

Which of the following statements about the microbial death rate is correct?

Accepted Answer

A constant percentage of the extant population is killed each minute

Question 4

Which of the following organisms is most resistant to antimicrobial agents?

Accepted Answer

Prions

Question 5

Why is moist heat generally more effective than dry heat for sterilization?

Accepted Answer

Moist heat denatures proteins and destroys cytoplasmic membranes more efficiently

Question 6

A laboratory is working with Ebola virus. Which biosafety level (BSL) is required for handling this pathogen?

Accepted Answer

BSL-4

Question 7

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

Accepted Answer

Boiling is not effective against bacterial endospores and some viruses

Question 8

Which of the following best explains why refrigeration slows microbial growth?

Accepted Answer

Refrigeration decreases the rate of chemical reactions and limits the availability of liquid water

Question 9

Which of the following chemical agents is classified as a high-level disinfectant and is effective against endospores?

Accepted Answer

Peracetic acid

Question 10

A food processing company wants to preserve fruit by inhibiting microbial growth. Which method would be most effective?

Accepted Answer

Increasing the osmotic pressure by adding high concentrations of sugar

Question 11

Which of the following statements about ionizing radiation is correct?

Accepted Answer

Ionizing radiation creates ions that disrupt hydrogen bonding and denature DNA

Question 12

Which of the following is a disadvantage of using gaseous agents such as ethylene oxide for sterilization?

Accepted Answer

They are often highly explosive and potentially carcinogenic

Question 13

A researcher is using a use-dilution test to evaluate a new disinfectant. What result indicates the disinfectant is most effective?

Accepted Answer

The disinfectant prevents all microbial growth at the highest dilution

Question 14

Which of the following best describes the mechanism of action of phenolics?

Accepted Answer

They disrupt cell membranes and denature proteins

Question 15

Why are nonenveloped viruses generally more resistant to harsh environmental conditions than enveloped viruses?

Accepted Answer

Nonenveloped viruses lack a lipid envelope, making them less susceptible to agents that disrupt membranes

Question 16

A patient is treated with hydrogen peroxide for a wound, but the treatment is ineffective. What is the most likely explanation?

Accepted Answer

Hydrogen peroxide is inactivated by catalase produced by human tissues

Question 17

Which of the following is a correct statement about the use of surfactants in microbial control?

Accepted Answer

Surfactants reduce surface tension and are good degerming agents

Question 18

Which of the following is a real-world example of the use of lyophilization?

Accepted Answer

Long-term preservation of microbial cultures

Question 19

A laboratory technician is using a HEPA filter in a biological safety cabinet. What is the primary function of the HEPA filter?

Accepted Answer

To remove airborne microbes from the air entering and exiting the cabinet

Question 20

Which of the following best explains why the use of antiseptic and disinfectant chemicals can promote the development of resistant microbes?

Accepted Answer

The use of these chemicals selects for microbes with resistance mechanisms, allowing them to survive and multiply

Controlling Microbial Growth in the Environment: Principles and Methods

Study Guide - Practice Questions