Question

External protective tissues are
A. Cortex and epidermis
B. Cork and pericycle
C. Cortex and pericycle
D. Cork and epidermis

Answer 1

Hint:- Protective tissues that are present in the outermost layer of the body are called external protective tissues, such as in stems, roots and leaves. They protect the body from infections, dehydration, injuries, etc.

Complete step-by-step solution:-
Epidermis is a single celled, compact and continuous layer present as the outermost layer in many parts of the plant such as roots, stems, flowers, and leaves. The cells present in this layer are parenchymatous in nature. Epidermis is covered with a cuticle which provides water resistance. Cuticle is made up of a waxy substance called cutin. Cuticle is not present in the roots. Epidermis protects the plant from injuries, water loss, infections by parasites, and regulates exchange of gases.When a plant grows older, the epidermis is replaced by a secondary meristem known as cork. Cork, also called phellem, is a non-living tissue present in the outer layer to stems in plants, and does not contain intercellular spaces between the cells (cells are compactly arranged). Cork has no protoplasm but it has tannins or resins present inside it. It provides resistance against water and pathogens (protective layer) and is formed during the secondary growth of the plant. The cell wall of cork is made up of a waxy substance called as suberin, which is not permeable to water or exchange of gases. Suberin has organic and fatty substances present which make the walls of the cork very thick.
Thus, the two types of external protective tissues are cork and epidermis. The correct option is (D) Cork and epidermis.

Note:- Cortex is a layer of cells present below the epidermis. Its main function is to store carbohydrates and other essential substances.
Pericycle is present in vascular tissue, encircling it. It is present in stems and roots.