question_answer 55)

  Cork cells are made impervious to water and gases by the presence of (a) cellulose                        (b) lipids                               (c) suberin          (d) lignin

Answer:

  (c) Cellulose is the basic of the cell wall present in plants. The cell wall of almost all the organism are made up of cellulose whereas lipids along with some proteins forms the basic building blocks of plasma membrane. Plasma membrane is semi permeable and it is not impervious to water. Lignin is a complex polymer which acts as a cement and hardens the cell wall. It provides flexibility, great tensile and compression strength to the cell wall and makes the eel; wail impermeable. It is present in scierenchyma cells and not in cork cells. The walls of cork cells are heavily thickened with an organic substance, suberin, Suberin makes these cells impervious to water and gases.