Answer:
1. The cells which are dead in the plants are called cork cells or phellem. The chemical content which is present in the walls of cork cells is suberin which makes the water and gases of the cells impermeable. The chemical layer of suberin forms a barrier for the movement of water and solute molecules. It also protects the plants against infection by various microorganisms and heat exposure.
2. Suberin is the component that is present in the cork cells. The internal tissues prevent the evaporation of cork cells. At the time of maturity, the cork cells become dead and replace the epidermis layer of the stem or root with the outer boundary. The suberin does not allow the water and gases to go outside of the cork cells. It is overall protecting cork cells that are present on the bark of trees.
Step-by-step explanation: