The outcome of the Gram stain is based on differences in the cell's:

• A. ribosomal RNA sequences
• B. cell wall structure
• C. flagellar arrangement
• D. plasma membrane composition

Answer: (B)

Verified step by step guidance

1. Understand that the Gram stain is a differential staining technique used to classify bacteria into two groups: Gram-positive and Gram-negative.
2. Recall that the key difference between Gram-positive and Gram-negative bacteria lies in their cell wall structure, specifically the thickness of the peptidoglycan layer.
3. Recognize that Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal violet stain, appearing purple under the microscope.
4. Know that Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, which does not retain the crystal violet stain but takes up the counterstain (safranin), appearing pink or red.
5. Conclude that the outcome of the Gram stain depends on the differences in the bacterial cell wall structure, not on ribosomal RNA sequences, flagellar arrangement, or plasma membrane composition.