List the characteristics of cork. How are they formed? Mention their role. [5 MARKS]

Characteristics : 2 Marks
Formation : 1 Mark
Function : 2 Marks

Characters:
(i) Cells of cork are dead at maturity.
(ii) These cells are compactly arranged and do not possess intercellular spaces.
(iii) Cells have a chemical substance called suberin in their walls.
(iv) Cells are several layers thick.

Formation:
As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells cut on the outer side by this meristem are called cork.

Functions:
They are protective in function for older stem/twigs/branches. They are impervious to gases and water.