Question 1

Which of the following is the correct protocol for cleaning glassware that previously contained live samples in the microbiology lab?

Accepted Answer

Boil for at least 15 minutes after the water is boiling, loosen caps, then wash and invert to dry.

Question 2

What is the primary purpose of using a Bunsen burner in aseptic technique?

Accepted Answer

To sterilize instruments and create a sterile field by incinerating contaminants.

Question 3

During a plate streaking for isolation, which error would most likely result in failure to isolate colonies?

Accepted Answer

Streak lines are not wide enough to cross from side to side.

Question 4

Which of the following best describes the difference between micro-morphology and macro-morphology in bacteria?

Accepted Answer

Micro-morphology is observed under the microscope and includes cell shape and arrangement; macro-morphology is observed on plates and includes colony shape, margin, and elevation.

Question 5

A student observes a bacterial colony with a lobate margin, convex elevation, and a shiny surface. Which term best describes the colony's macro-morphology?

Accepted Answer

Lobate, convex, shiny

Question 6

Which equation should be used to calculate the size of a specimen observed under the microscope, given the number of squares it occupies and the diameter of the field of view?

Accepted Answer

$$\{SS\} = \frac{\{Target\} \cdot \{FoV\ size\}}{\{D\}}$$

Question 7

Which of the following is NOT a correct step in the aseptic transfer of bacteria from a broth culture?

Accepted Answer

Waft the instrument to cool it after incineration.

Question 8

Which bacterial shape is described as a helical form with flexible bodies and moves by axial filaments?

Accepted Answer

Spirochete

Question 9

In the Gram stain protocol, what is the function of the mordant (iodine)?

Accepted Answer

It binds the crystal violet to the cell wall, increasing retention in Gram-positive cells.

Question 10

Which media is specifically designed to grow hemoglobin-dependent pathogens and is used for throat swab samples?

Accepted Answer

BAP (Blood Agar Plate)

Question 11

A student is preparing a negative stain. Which step is essential to avoid false results?

Accepted Answer

Air dry the slide completely before counterstaining.

Question 12

Which of the following is a correct statement about the use of the microscope in microbiology labs?

Accepted Answer

Always start at the lowest magnification (4x) and scan the entire slide before increasing magnification.

Question 13

Which of the following is a key reason for using a flowchart in the identification of an unknown microorganism?

Accepted Answer

To systematically eliminate possibilities using evidence-based decision-making, one test at a time.

Question 14

Which of the following is a property of acid-fast bacteria that makes them resistant to Gram staining?

Accepted Answer

High concentration of mycolic acids in the cell wall.

Question 15

In the catalase test, what result indicates a positive reaction?

Accepted Answer

Effervescence (bubbling) after adding H2O2.

Question 16

Which of the following is the correct interpretation of a DNase test plate showing a zone of clearing around the colony?

Accepted Answer

The organism is DNase positive.

Question 17

Which of the following is a critical rule for maintaining a laboratory notebook?

Accepted Answer

Record all data, including negative or unexpected results, in pen.

Question 18

Which of the following is the correct protocol for labeling plates and tubes prior to inoculation?

Accepted Answer

Label plates on the bottom (agar side) around the rim and tubes lengthwise without inclining the tube.

Question 19

Which of the following is a correct statement about the use of media in microbiology?

Accepted Answer

TSA is a general-purpose medium, while SDA is acidic and used for fungi.

Microbiology Laboratory Study Guide: Techniques, Morphology, and Biochemical Assays

Study Guide - Practice Questions

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