Question 1

Which of the following best describes a chemoheterotroph in terms of its energy and carbon sources?

Accepted Answer

Uses organic compounds as both energy and carbon sources.

Question 2

A microbiologist wants to isolate a pure culture of a bacterium from a mixed sample. Which plating method is most appropriate for obtaining isolated colonies?

Accepted Answer

Quadrant streak plate method

Question 3

Which of the following best defines 'thermal death time'?

Accepted Answer

The time required to kill all microorganisms in a liquid suspension at a given temperature.

Question 4

A hospital is choosing a disinfectant for surgical instruments. Which property is LEAST important for an ideal disinfectant?

Accepted Answer

Pleasant odor

Question 5

Which of the following media types is specifically designed to distinguish between organisms based on their metabolic properties?

Accepted Answer

Differential media

Question 6

A researcher is culturing a bacterium that requires vitamins and trace metals for growth. Which type of media should be used to ensure all nutritional requirements are met?

Accepted Answer

Enriched/fortified media

Question 7

Which of the following statements about moist heat sterilization is correct?

Accepted Answer

It denatures proteins more efficiently due to increased kinetic energy of water molecules.

Question 8

A laboratory is using UV radiation to sterilize surfaces. Which property of UV light is most responsible for its germicidal effect?

Accepted Answer

High frequency and short wavelength

Question 9

Which of the following best describes the relationship between wavelength ($$\lambda) $$and frequency ($$f) of $$electromagnetic radiation?

Accepted Answer

They are inversely proportional: $$f = \dfrac{c}{\lambda}$$

Question 10

A solution is treated with a chemical that inhibits bacterial growth but does not kill the bacteria. This chemical is best described as a:

Accepted Answer

Bacteriostatic agent

Question 11

A microbiologist is comparing the effectiveness of two sterilization methods. Method A reduces the microbial population from $$10^6 to$$ $$10^2 in 10 $$minutes. What is the decimal reduction time ($$D$$ value) for Method A?

Accepted Answer

$$D = 2.5$$ minutes

Question 12

Which of the following is an example of a defined (synthetic) medium?

Accepted Answer

A medium with known quantities of glucose, ammonium sulfate, and magnesium chloride

Question 13

A culture is described as 'opaque, mucoid, and with irregular margins.' These are examples of which type of characteristics?

Accepted Answer

Cultural characteristics

Question 14

Which of the following best explains why membrane filtration is used for sterilizing heat-sensitive solutions?

Accepted Answer

It physically removes microorganisms without exposing them to high temperatures.

Question 15

A laboratory technician is using lyophilization to preserve bacterial cultures. What is the main principle behind this method?

Accepted Answer

Removal of water by freezing and sublimation

Question 16

Which of the following best describes the function of a selective medium?

Accepted Answer

It inhibits the growth of some organisms while allowing others to grow.

Question 17

A patient with a wound infection is treated with a chemical that kills both bacteria and fungi. This chemical is best classified as a:

Accepted Answer

Germicide

Question 18

Which of the following is a disadvantage of using dry heat sterilization compared to moist heat sterilization?

Accepted Answer

It requires longer exposure times and higher temperatures.

Question 19

A laboratory is testing the effectiveness of a new disinfectant. After 5 minutes, the number of viable bacteria drops from $$10^5 to$$ $$10^3. $$What is the log reduction achieved?

Accepted Answer

$$2$$

Question 20

Which of the following best describes the process of degerming?

Accepted Answer

Removing microbes from a limited area, such as skin before injection

Bacterial Culturing and Sterilization: Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard