Question 1

Which of the following best describes the process of binary fission in bacteria?

Accepted Answer

A single cell divides into two genetically identical daughter cells after chromosome replication and septum formation.

Question 2

A hospital patient develops a persistent infection on an indwelling catheter. Which microbial growth phenomenon is most likely responsible for the difficulty in treating this infection?

Accepted Answer

Biofilm formation by bacteria on the catheter surface.

Question 3

Which of the following equations correctly calculates the generation time ($$g) $$for a bacterial culture?

Accepted Answer

$$g = \frac{t}{n}$$, where $$t is $$the total growth time and $$n is $$the number of generations.

Question 4

Which growth phase in a closed batch culture is characterized by an equal rate of cell division and cell death?

Accepted Answer

Stationary phase

Question 5

A bacterium isolated from a hot spring grows optimally at 70°C. How would you classify this organism based on its temperature preference?

Accepted Answer

Thermophile

Question 6

Which of the following best explains why halophiles can survive in high-salt environments?

Accepted Answer

They maintain a high concentration of organic materials and ions in their cytoplasm to prevent plasmolysis.

Question 7

Which enzyme is responsible for converting superoxide ions to hydrogen peroxide in aerobic bacteria?

Accepted Answer

Superoxide dismutase

Question 8

A microbe that grows best at pH 3 and is isolated from a volcanic vent is most likely a(n):

Accepted Answer

Acidophile

Question 9

Which of the following statements about selective and differential media is correct?

Accepted Answer

Mannitol salt agar is both selective (due to high salt) and differential (due to mannitol fermentation).

Question 10

Which of the following methods would be most appropriate for sterilizing a heat-sensitive plastic medical device?

Accepted Answer

Ethylene oxide gas treatment

Question 11

A laboratory technician needs to enumerate the number of viable bacteria in a water sample. Which method should they use?

Accepted Answer

Viable plate count with serial dilution

Question 12

Which of the following best describes a chemoheterotroph?

Accepted Answer

An organism that obtains energy from chemical compounds and carbon from organic sources.

Question 13

Which physical method is most effective for ensuring the elimination of bacterial endospores from surgical instruments?

Accepted Answer

Autoclaving at 121°C and 15 psi for 20 minutes

Question 14

A microbiologist is working with a fastidious organism. What type of growth medium should be used?

Accepted Answer

Complex (enriched) medium

Question 15

Which of the following statements about prion control is correct?

Accepted Answer

Prions require a combination of chemical treatments and increased temperature and pressure during autoclaving for elimination.

Question 16

Which of the following is a correct statement about the decimal reduction time ($$D$$ value) in microbial control?

Accepted Answer

$$D$$ value is the time in minutes required to kill 90\% of a microbial population at a given temperature.

Question 17

Which of the following best explains why Mycobacterium tuberculosis is difficult to control with standard disinfectants?

Accepted Answer

It has a cell wall rich in waxy mycolic acids that resist chemical penetration.

Question 18

Which of the following is a distinguishing feature of an obligate anaerobe?

Accepted Answer

It cannot survive in the presence of oxygen due to inability to detoxify reactive oxygen species.

Question 19

A sample is collected from a soda lake with a pH of 10. Which type of microorganism is most likely to be isolated from this environment?

Accepted Answer

Alkaliphile

Question 20

Which of the following statements about HEPA filters is correct?

Accepted Answer

HEPA filters remove 99.97\% of airborne particles with a pore size of 0.3 micrometers or larger, but do not sterilize air.

Fundamentals of Microbial Growth and Decontamination: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard