Question 1

Which primary stain and counterstain are used in the Schaeffer-Fulton endospore staining method?

Accepted Answer

Primary: Malachite green; Counterstain: Safranin

Question 2

In the acid-fast stain, what color will Mycobacterium smegmatis appear under the microscope, and what component of its cell wall is responsible for this result?

Accepted Answer

Pink/red; mycolic acid

Question 3

During capsule staining, which combination of stains is used to visualize the capsule as a clear halo?

Accepted Answer

Congo red and acid fuchsin

Question 4

A student observes a slide stained with the Schaeffer-Fulton method and sees green ovals inside pink/red rods. What is the correct interpretation?

Accepted Answer

Endospores are present inside vegetative cells

Question 5

Which flagellar arrangement describes a bacterium with flagella distributed all around its surface?

Accepted Answer

Peritrichous

Question 6

Why is heat or a high concentration of phenol required during acid-fast staining?

Accepted Answer

To drive the carbol fuchsin into the waxy mycolic acid-rich cell wall

Question 7

Which of the following best explains why endospores are resistant to ordinary staining methods?

Accepted Answer

Their tough outer layers prevent stain penetration

Question 8

A clinical sample is stained with acid-fast stain and appears blue under the microscope. What does this indicate about the organism?

Accepted Answer

It is not acid-fast and lacks mycolic acid in its cell wall

Question 9

Which of the following is a key virulence factor for bacteria that produce capsules?

Accepted Answer

Prevention of phagocytosis

Question 10

A sample of Bacillus subtilis is stained using the Schaeffer-Fulton method after 72 hours of incubation. What result would you expect and why?

Accepted Answer

More green endospores due to nutrient depletion

Question 11

Which of the following best describes the appearance of a capsule-positive bacterium after capsule staining?

Accepted Answer

Red cell with a clear halo against a red background

Question 12

What is the function of a mordant in flagella staining?

Accepted Answer

To coat and thicken the flagella so they are visible under light microscopy

Question 13

Which of the following organisms would you expect to be acid-fast positive?

Accepted Answer

Mycobacterium smegmatis

Question 14

A student performs a capsule stain and observes no clear halos around the cells. Which of the following is the most likely explanation?

Accepted Answer

The organism does not produce a capsule

Question 15

Which of the following best describes the role of mycolic acid in acid-fast bacteria?

Accepted Answer

It makes the cell wall waxy and impermeable to many stains

Question 16

Which flagellar arrangement would you expect to find in Proteus vulgaris?

Accepted Answer

Peritrichous

Question 17

A patient sample is stained with the Ziehl-Neelsen method and shows pink/red rods. What disease might this indicate, and why?

Accepted Answer

Tuberculosis, because Mycobacterium tuberculosis is acid-fast

Question 18

Which of the following best explains why capsule staining is considered a negative stain technique?

Accepted Answer

The capsule does not take up the stain, leaving a clear halo

Question 19

During the endospore staining procedure, what is the purpose of steaming the slide while applying malachite green?

Accepted Answer

To drive the stain into the tough endospore coat

Question 20

Which of the following best describes the appearance of a non-acid-fast organism after acid-fast staining?

Accepted Answer

Blue due to methylene blue counterstain

Structural and Differential Stains in Microbiology: Endospore, Capsule, Flagella, and Acid-Fast Stains

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