Question

question 7 which of the following pairs is mismatched? a methylene blue — positive stain b nigrosin — negative stain c basic dye — negative stain d crystal violet — positive stain

Explanation:

Basic dyes are positively - charged and are used for positive staining as they are attracted to the negatively - charged components of cells. Negative stains use acidic dyes. Methylene blue, crystal violet are basic dyes and positive stains. Nigrosin is an acidic dye and a negative stain.

Answer:

C. basic dye — negative stain