STANDARD Zoology Bacterial Cell Structure MCQ Question

Gram positive bacteria differ from Gram negative bacteria as they have different components of cell wall. The cell wall of Gram positive bacteria contains a thick peptidoglycan layer with teichoic acids while the cell of Gram negative bacteria contains a thin peptidoglycan layer without teichoic acids. Gram positive bacteria can retain the gram stain and appear purple because the thick layer of peptidoglycan traps the stain. On the other hand, Gram negative bacteria appear bright pink or red because they have only a thin peptidoglycan layer sandwiched between two lipid layers. So, the correct answer is option B.