Question

multiple choice: choose the correct answer.

1. what is the primary stain used in the acid - fast stain?

a) crystal violet
b) safranin
c) carbolfuchsin
d) malachite green

1. why is heat applied during acid - fast staining?

a) to kill bacteria
b) to fix the smear
c) to help stain penetrate the waxy cell wall
d) to evaporate excess stain

1. what is used to decolorize non - acid - fast cells?

a) water
b) acid - alcohol
c) ethanol
d) iodine

1. what color do acid - fast bacteria appear after staining?

Explanation:

1. In acid - fast staining, carbolfuchsin is the primary stain. It can bind to the mycolic acids in the cell wall of acid - fast bacteria.
2. Heat is applied during acid - fast staining to help the carbolfuchsin stain penetrate the waxy cell wall of acid - fast bacteria.
3. Acid - alcohol is used to decolorize non - acid - fast cells. Non - acid - fast cells lose the primary stain when treated with acid - alcohol.
4. Acid - fast bacteria retain the carbolfuchsin stain and appear red after staining.

Answer:

1. c) Carbolfuchsin
2. c) To help stain penetrate the waxy cell wall
3. b) Acid - alcohol
4. Red (not provided as an option in the original list but the correct color result for acid - fast bacteria after staining)