Question

Waxy coating on the epidermis of the young stem is called?
A. Suberin
B. Periderm
C. Phellem
D. Cuticle

Answer 1

In plants originating from the protoderm, the epidermis is the outermost layer of cells covering the stem, roots, leaves, flowers, fruits, and seed components. It is the best-known structural component of the cuticular membrane, a polyester polymer composed of inter-esterified omega hydroxy acids cross-linked by ester and epoxide bonds.

Complete answer:
The epidermis forms a protective layer around the plant to protect it from mechanical damage, loss of water, and infection. Suberin is a waxy waterproofing material that is used in taller plants. Suberin is a significant cork constituent and is named after Quercus suber , the cork oak. Its primary role is as an obstacle to the passage of solutes and water. Suberin is present in specialized plant cell walls as a lipophilic molecule. It prevents the loss of water in the cells, protects the plant from infection, and plays a very important role in the process of wound healing. Suberin mainly forms the peridermis that envelops the secondary stem.
The peridermis is the secondary (dermal) tissue that replaces an epidermis with gymnosperms and dicotyledons when stem and root thickness are formed. The periderm is the outer layer covering the secondary stem in older plants and is formed in response to damage or infection. The secondary stem is not a young stem, so this choice is wrong.
Phellem (cork) consists of cells that are dead at maturity and the secondary wall, consisting of parallel suberin lamellae alternating with wax layers, covers their primary walls from the inside. Phellem (or cork) is the secondary tissue that forms the peridermal outer layer and originates from the cork cambium. This choice is therefore incorrect.
A cuticle is a waxy layer present on a young stem's epidermis that normally cuts water loss through transpiration. The cuticle is a material based on waxy lipids and hydrocarbons formed specifically by the epidermal cells of the aerial parts of the plant, particularly in parts of the plant that do not have a peridermis. This is the substance around young stems that forms the waxy layer. This choice is therefore right.
Therefore, the correct answer to this question is (D), i.e., The waxy coating on the epidermis of the young stem is called “Cuticle”.

Note: The cuticle layer present in the leaves prevents the entry of gases into the cells. When the stomata open up for carbon dioxide intake, the cuticle protects the mesophyll cells that are photosynthesized by building a transparent membrane over them.