Question

The protective non-cellular layer found on the outside of plant organs is
(a)Epiblema
(b)Velamen
(c)Cuticle
(d)Cork

Answer 1

Hint: Plant organs are protected by a layer of lipid polymers impregnated with waxes that is present on the outer surfaces of the primary organs of all vascular plants. It is the outermost layer interacting with the environment. It is also present in the sporophyte generation of hornworts, and in both sporophyte and gametophyte generations of mosses.

Complete answer:
The non-cellular layer that protects the outer covering of plant organs is the cuticle. It is a protective film covering the epidermis of leaves, young shoots, and other aerial plant organs without periderm. It consists of lipid and hydrocarbon polymers impregnated with wax. And it is synthesized exclusively by the epidermal cells. The plant cuticle forms a coherent outer covering of the plant. The cuticle is composed of an insoluble cuticular membrane impregnated by and covered with soluble waxes. Cutin, a polyester polymer composed of inter-esterified omega hydroxy acids which are cross-linked by ester and epoxide bonds, is the best-known structural component of the cuticular membrane. The cuticle can also contain a non-saponifiable hydrocarbon polymer known as Cutan. The cuticular membrane is impregnated with cuticular waxes and covered with epicuticular waxes, which are mixtures of hydrophobic aliphatic compounds, hydrocarbons.

Additional Information:
 -The plant cuticle serves as a barrier to prevent excessive transpirational water loss allowing gas exchange and transpiration to be dynamically controlled by stomata.
-It also provides protection against desiccation and external environmental stresses.
-It consists of Cutin, a waxy, water-repellent substance allied to suberin, which is found in the cell walls.
So, the correct answer is 'Cuticle’

Note:
 -The cuticle is usually thicker on the upper surface of the leaf than on the underside.
-The cuticle is not merely a mechanical shield. The increasing research on plant leaves has revealed the roles of the plant cuticle in resistance against a variety of plant pathogens.
- The fruit cuticle also serves as an important determinant of fruit defense and quality.