Biological Classification Question 38
38. The main difference in Gram (+)ve and Gram $(-)$ ve bacteria resides in their
(a) cell wall
(b) cell membrane
(c) cytoplasm
(d) flagella
Show Answer
Answer : a
Hints & Solutions
(a) Gram +(ve) and Gram -(ve) bacteria are separated on the basis of their cell wall composition. Christian Gram, on the basis of staining behaviour of the cell wall with Gram’s stain, grouped bacteria into Gram +ve and Gram -ve type. The bacteria which retain blue or purple colour after staining are Gram +ve e.g. Bacillus subtilis and which loses blue colour is Gram-ve e.g. E. coli. In Gram-ve, stain is washed due to high lipid content in the cell having thick wall, Gram +ve has single layered cell wall rich in peptidoghycans which retain the colour.
