Gram positive bacteria appear_______________?
Correct answer: A. Purple
- A. Purple
- B. Red
- C. Pink
- D. Blue
Explanation
Gram-positive bacteria retain the crystal violet-iodine complex because their thick peptidoglycan wall is not effectively decolorised, so they appear purple under the microscope. Students may choose red or pink by recalling the colour of Gram-negative bacteria after the counterstain instead.
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