Which term is the classification of bacteria that do not hold a dye stain under a microscope?

Which term is the classification of bacteria that do not hold a dye stain under a microscope?

• A. Gram Negative
• B. Anaerobes
• C. Bacilli
• D. Cocci

Answer: (A)

Grams staining distinguishes bacteria by how their cell walls interact with dye during the staining process. The group that does not retain the primary dye after the decolorizing step is Gram-negative. Their thin peptidoglycan layer and outer membrane prevent the dye from sticking, so they are washed clean and then take up the counterstain, appearing pink or red under the microscope. The other terms describe shape (rod-shaped bacilli, spherical cocci) or oxygen needs (anaerobes) rather than dye retention, so they don't describe this staining behavior.

Grams staining distinguishes bacteria by how their cell walls interact with dye during the staining process. The group that does not retain the primary dye after the decolorizing step is Gram-negative. Their thin peptidoglycan layer and outer membrane prevent the dye from sticking, so they are washed clean and then take up the counterstain, appearing pink or red under the microscope. The other terms describe shape (rod-shaped bacilli, spherical cocci) or oxygen needs (anaerobes) rather than dye retention, so they don't describe this staining behavior.