Question

Casparian strips are present in _______ of the root.
A) Epiblema
B) Cortex
C) Pericycle
D)Endodermis

Answer 1

Hint:Casparian strips are present in the innermost cortical layer of the dicot root. It is different from the other cell wall.

Complete answer:
First we should know about Casparian strips to answer this question. A band of cell wall material is the Casparian strip which is chemically distinct from the rest of the cell wall. Generally, the walls of the cells are mostly composed of lignin and without suberin, while suberin and occasionally lignin made the Casparian strip.
Now, let us find the solution from the options-
>Epiblema is the root’s single outermost layer. With the presence and occurrence of unicellular root hairs of plants, it is often shadeless, colourless, polygonal without any intercellular spaces. In epiblema, the Casparian strips are not found. Therefore, the option A is incorrect.
>The endodermal cells do not facilitate wall to wall movement of substances between the cortex and the pericycle, due to the presence of Casparian strips. Substances must reach the endodermal cell cytoplasm. Therefore, the option B and C are incorrect.
>The innermost layer of the cortex is commonly believed to be the endodermis. It consists of a single layer of cells that are barrel-shaped and do not embed intercellular spaces. There is a thickening band in the young endodermal cells that extends along their radial and tangential walls. The Casparian strip is called this band of thickening. Both suberin and lignin are made of it. Casparian strips avoid endodermal cell plasmolysis.

Additional information: In secondary growth angiosperms and gymnosperms and, the roots usually only produce endodermis with Casparian bands. In all of these, as the peridermis emerges from the pericycle, the endodermis is later discarded, along with the cortex. Either the endodermis is extended or crushed whether the pericycle is superficial and the cortex is preserved, or it maintains pace with the vascular cylinder extension by radial anticlinal divisions, and the new walls grow Casparian stripes in continuity with the existing ones.

Thus, the correct answer is option D Endodermis.

Note:Since the outer development of the cortex is done, the Casparian stripes separate. The primary xylem of its vascular cylinder is only partially advanced at this stage of root growth.