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  Biology (NTSE/Olympiad)  

2. Tissue

Protective Tissue

Protective Tissue :
It includes epidermis and cork.
Epidermis :
It is usually present in the outermost layer of the plant body such as leaves, flowers, stem and roots.
Epidermis is one cell thick and is covered with cuticle.
Cuticle is a water proof layer of a waxy substance called cutin which is secreted by epidermal cells.
The main function of epidermis is to protect the plant from desication and infection.
Cork :
As roots and stem grow older with time (increase in girth), tissues at the periphery become cork cell.
Cork cells are dead cells and they do not have any intercellular spaces.
The walls of cork cells are heavily thickened by the deposition of an organic substance (a fatty substance), called suberin.
Cork is protective in function. cork cells prevent desiccation (loss of water from plant body), infection and mechanical injury.
Cork is produced by cork cambium commereially it is obtained from oak (quercus suber).
Cork is used for making insulation boards, sports goods, bottle corks etc.

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