Question 1

Which of the following best describes the purpose of flaming and cooling the inoculating loop between each quadrant during the streak plate method, as shown in the first image?

Accepted Answer

To sterilize the loop and prevent contamination between quadrants.

Question 2

A bacterial colony with a 'filamentous' form, 'umbonate' elevation, and 'lobate' margin would most likely appear as:

Accepted Answer

A colony with thread-like projections, a raised center, and deeply lobed edges.

Question 3

The structures shown in the third image are characteristic of which fungal organism, and what is the primary function of these structures?

Accepted Answer

Histoplasma capsulatum; reproduction and dispersal.

Question 4

Which of the following statements about the organism shown in the fourth image is correct?

Accepted Answer

It is Aspergillus, an opportunistic pathogen that can produce aflatoxin.

Question 5

In the fifth image, which tube contains motile bacteria and what is the evidence?

Accepted Answer

The tube on the right; turbidity extends away from the stab line.

Question 6

The arrangement of flagella shown in the sixth image is best described as:

Accepted Answer

Peritrichous

Question 7

Which flagellar arrangement allows a bacterium to have a single flagellum at each end, as shown in the seventh image?

Accepted Answer

Amphitrichous

Question 8

In the eighth image, what is the significance of the 'run and tumble' behavior for bacterial motility?

Accepted Answer

It allows bacteria to move toward attractants or away from repellents by alternating straight runs and random tumbles.

Question 9

The ninth image shows a bacterial endospore stain. Which dye stains the endospore, and what is the function of the endospore?

Accepted Answer

Malachite green; survival in harsh conditions.

Question 10

The tenth image shows a Gram stain of Bacillus anthracis from a diseased cow. Which disease is most likely, and what is a key feature of this bacterium?

Accepted Answer

Anthrax; it forms endospores.

Question 11

The apparatus shown in the eleventh image is used for which purpose in microbiology?

Accepted Answer

Creating anaerobic conditions for culturing obligate anaerobes.

Question 12

The twelfth and thirteenth images show antibiotic disk diffusion tests. What is the formal name of this test, and how is antibiotic susceptibility determined?

Accepted Answer

Kirby-Bauer test; by measuring the diameter of the zone of inhibition and comparing to a standard table.

Question 13

Which of the following best explains why a larger zone of inhibition does NOT always mean an antibiotic is more effective in the Kirby-Bauer test?

Accepted Answer

Zone size is affected by the diffusion rate of the antibiotic, not just its effectiveness.

Question 14

Which of the following is the correct order of reagents used in the Gram stain procedure?

Accepted Answer

Crystal violet, iodine, ethanol, safranin

Question 15

Which of the following best describes the difference between fungal spores and bacterial endospores?

Accepted Answer

Fungal spores are for reproduction; bacterial endospores are for survival.

Question 16

Which of the following media would be best for isolating single colonies from a mixed bacterial culture?

Accepted Answer

Agar plate using the streak plate method

Question 17

Which of the following terms describes bacterial growth that forms a ring at the surface of a broth culture?

Accepted Answer

Pellicle

Question 18

Which of the following is the main reason hand washing is important in preventing disease transmission, even though it does not remove all bacteria?

Accepted Answer

It removes transient microbes that may be pathogenic.

Question 19

Which of the following best describes the function of mycolic acid in Mycobacterium cell walls?

Accepted Answer

It provides resistance to desiccation and chemical damage, making the cells acid-fast.

Microbiology Laboratory Techniques and Concepts: Lab Exam 1 Study Guide

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