Question

External protective tissues of plants are (of dicot stem are) [BHU 1980; CPMT 1984]
A) Cork and pericycle
B) Cortex and epidermis
C) Pericycle and cortex
D) Epidermis and cork

Answer 1

External protective tissues of plants are (of dicot stem are)
➡️ Cortex and epidermis

Answer 2

The right option is (D)

External protective tissues of plants of dicot stem are Epidermis and Cork.

(1) During extrastellar secondary growth epidermis , pericycle , parenchyma or collenchyma cells acquire secondary meristematic property by the phenomenon of the de-differentiation and is denoted as phellogen/cork cambium.

(2) Outer layer of the cambium lose their protoplast and are dead.

(3 ) Cell walls become thick and they constitute cork or phellem.

(3) The phelloderm, phellogen and phellem together form the primary layer for covering when the epidermis gets damaged.