Question

question 12
bacterial smears are fixed before staining to
a make their walls permeable.
b accept stain.
c make the cells visible.
d affix the cells to the slide.

Explanation:

Fixing bacterial smears before staining is mainly to attach the cells firmly to the slide so that they do not wash away during the staining process. It is not to make walls permeable (A), as that is not the main purpose. Staining agents are designed to interact with cells regardless of fixing for permeability - related reasons. Fixing is not directly related to making cells accept stain (B) as the nature of the cell components and the staining agent are more relevant for stain - acceptance. Making cells visible (C) is mainly the role of the stain itself, not the fixing step.

Answer:

D. affix the cells to the slide.