VMC-0091
QUESTION
Primary stain used in Gram’s stain is?
OPTIONS
(A) Lipid soluble
(B) Water soluble
(C) Low molecular weight
(D) High molecular weight
ANSWER
(B) Water soluble
EXPLANATION
The primary stain in Gram staining is crystal violet (gentian violet), which is a water-soluble basic/cationic dye. It initially stains both Gram-positive and Gram-negative bacteria purple. Gram’s iodine then acts as a mordant, forming a crystal violet–iodine complex.
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