what is cork class 9

For Class 9 Biology (NCERT/CBSE), cork is a protective tissue found in the outer region of older stems and roots of plants. It replaces the epidermis when the plant grows in thickness and forms the outer bark.

Short definition (Class 9 level)

• Cork is a protective tissue made of dead cells that forms the outer covering (bark) of older stems and roots.

• Its cell walls contain a fatty substance called suberin , which makes them waterproof and airproof.

Main features of cork

• Cells are dead and compactly arranged , with no intercellular spaces.

• Cell walls have suberin , so water and gases cannot pass through easily.

• Cells are hollow and filled with air, making the layer light.

How cork is formed (Class 9 idea)

• In older stems, a special meristematic layer called cork cambium (phellogen) develops.

• This cambium divides and produces cork cells towards the outside, which gradually die and form the bark.

Functions of cork

• Protects inner tissues from mechanical injury (physical damage).

• Prevents water loss from the plant surface due to suberin, which reduces evaporation.

• Acts as a barrier against pathogens and harmful environmental factors.

Daily-life connection

• The cork used as bottle stoppers , notice boards, and insulation sheets is obtained from the bark of the cork oak tree, which is rich in this tissue.

One-line exam answer:
Cork is a protective tissue made of dead, suberized, compactly arranged cells that forms the outer covering of older stems and roots and prevents water loss and mechanical injury.