Question 1

A hospital is preparing surgical instruments for reuse. Which method should be used to ensure complete elimination of all bacteria, viruses, and endospores from the instruments?

Accepted Answer

Sterilizing with an autoclave

Question 2

Which phase of the bacterial growth curve is characterized by a balance between cell division and cell death, often due to nutrient depletion and waste accumulation?

Accepted Answer

Stationary phase

Question 3

A microbiologist isolates a bacterium from a soda lake with a pH of 10. Which classification best describes this organism based on its pH preference?

Accepted Answer

Alkaliphile

Question 4

Which of the following statements about halophiles is correct?

Accepted Answer

They thrive in high-salt environments, such as the Dead Sea.

Question 5

A culture of Staphylococcus aureus is able to grow in both high and low salt concentrations, but grows best at low salt. What term best describes this organism's salt tolerance?

Accepted Answer

Facultative halophile

Question 6

Which of the following best describes an obligate anaerobe?

Accepted Answer

Cannot use oxygen and is killed by its presence due to inability to eliminate reactive oxygen species.

Question 7

Which of the following equations represents the conversion of superoxide ions to hydrogen peroxide by superoxide dismutase?

Accepted Answer

$$2\ \mathrm{O}_2^- + 2\ \mathrm{H}^+ \rightarrow \mathrm{H}_2\mathrm{O}_2 + \mathrm{O}_2$$

Question 8

A researcher is growing bacteria that require an external source of organic carbon, such as glucose, for growth. What is the correct classification for these bacteria?

Accepted Answer

Heterotrophs

Question 9

Which of the following is a correct statement about nitrogen requirements for microorganisms?

Accepted Answer

Some microorganisms can fix atmospheric nitrogen directly.

Question 10

Which of the following is NOT considered an organic growth factor for microorganisms?

Accepted Answer

Iron

Question 11

A laboratory is testing the effectiveness of a new germicide. Which factor is LEAST likely to influence the choice of microbial control method?

Accepted Answer

Color of the item being disinfected

Question 12

Which of the following best differentiates between thermal death time and thermal death point?

Accepted Answer

Thermal death time is the shortest time needed to kill all microbes at a certain temperature; thermal death point is the minimum temperature needed to kill all microbes in 10 minutes.

Question 13

Which of the following chemical agents is classified as a high-level germicide and is capable of achieving sterility at certain concentrations?

Accepted Answer

Aldehydes

Question 14

A patient with a wound is treated with a chemical agent that targets proteins and lipid membranes, is cheap, easily applied, and can be used as both a disinfectant and antiseptic. Which agent is most likely being used?

Accepted Answer

Alcohol (e.g., isopropanol)

Question 15

Which of the following methods is most appropriate for sterilizing heat-sensitive plastic Petri dishes?

Accepted Answer

Ethylene oxide gas

Question 16

Which of the following is the most common action of chemical methods of microbial control?

Accepted Answer

Damage to proteins

Question 17

Which group of microbes is the most resistant to antimicrobial agents, and why?

Accepted Answer

Prions, because they withstand autoclaving and chemical sterilization

Question 18

A public health official needs to quickly eliminate most pathogenic bacteria, protozoans, and viruses from contaminated drinking water. Which method is most appropriate?

Accepted Answer

Boiling water for 5 minutes

Question 19

Which of the following best explains why endospores are highly resistant to many antimicrobial agents?

Accepted Answer

They can revert to vegetative cells when conditions improve and survive extreme conditions.

Question 20

A laboratory is tasked with sterilizing a heat-sensitive chemical powder. Which method should be used?

Accepted Answer

Radiation

Microbial Growth and Control: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards