36. Long answer questions V

 

When the cork matures, the cells are deadlive. These cells are arranged tightly. Intercellular spaces do not exist in cells. A chemical called ligninsuberinpectincellulose is found in the walls of cells. They have singleseveral layers. Water and gases cannot penetrate the cork.

 

The outer protective tissue of the plants changes as they get older. A secondary meristem called the vascular cambiumcork cambiumcortex replaces the epidermis in the stem. It is a simple tissue made up of rectangular cells and vacuolated protoplasts. The cork cambium creates new cells on both sides, forming a cork outside and a secondary cortex inside. Dead, closely packed cork cells lack intercellular spaces and are arranged compactly.

 

Suberin, a substance that thickens the cell walls of cork cells, it prevents water and gases from passing through themIt provides protection to the plants and prevents water lossit protects against mechanical injury and infection of the plantsall the above