Question

What is cork? Why does it act as a protective tissue?

Answer 1

Hint: Cork is a layer of the bark of plants and has several commercial uses. It is made of the dead cells which are compactly arranged with a covering of waxy material, which in turn gives cork its impermeable buoyant characteristics.

Complete answer:
Cork cambium, is an epidermal tissue layer that is present between the cork and primary phloem. It is a lateral meristem and contributes to the secondary growth of the plant. This gives rise to the tough protective material named cork.
Cork is the phellem layer of the bark and consists of irregularly shaped, thin-walled cells that have a coating of wax which makes them almost impermeable. Cork makes the peeling bark of many trees but it is not vital to the tree's survival and function. It's only noticeable function is to protect the tree from unsuitable conditions.
The cork of some plants such as oak has very popular commercial uses. These are used for making things like bottles, fishing floats, buoys floats, handles for fishing rods, etc.
The structure and arrangements of the cells in the cork layer of bark make it very strong and give it the ability to protect the tree from unsuitable conditions. The cells of cork are mostly dead and compactly packed together with no almost no Intercellular space. With that, a layer of the suberin (waxy substance) is present coating the cells which prevent the entry of water and gases and make it impermeable. Thus, the structure of cork allows it to protect the plant from mechanical injury as well as prevents evaporation in extensive heat. It acts as an external barrier to protect the plant from external forces and also gives good insulation due to its hard and rigid structure.

Note: The cork of oak tree is known as cork oak and is found abundantly in Portugal, Spain, Southern France and Italy, and North America. The outer cork of these trees protect them from the heat and dry winds of the Mediterranean summer and is used commercially to produce bottles of wine and other alcoholic beverages. The self-life of these cork oak is about 150 years.