Question

Endodermis acts as a biological check post and prevents wall to wall flow of materials because it has
A. Casparian strips
B. Barrel-shaped cells
C. Passage cells
D. Specialized thickenings

Answer 1

A specialized tissue in the roots and stems of vascular plants, composed of a single layer of modified parenchyma cells forming the inner boundary of the cortex. The endodermis is the boundary between the cortex and the stele.

Complete answer: In the endodermal cells, lingo-suberised thickenings are present on the radial and tangential cell walls. These are called the Casparian strip. Due to this, endodermis acts as a biological check post and prevents walls to flow materials.
-The endodermis is developmentally the innermost portion of the cortex. It consists of a single layer of barrel-shaped cells without any intercellular spaces or sometimes several cell layers.
-The passage cells are the thin-walled suberized cells, which are found in the endodermis of vascular plants often opposite the protoxylem strands. These are also called transfusion cells.
-The ground tissue of plants includes all tissues that are neither dermal nor vascular. It is a Tissue specialized for food storage and is commonly formed of parenchyma cells. This leads to specialized thickening.
Hence, the correct answer is Option A.

Note: The suberin is the main component of the Casparian strip. Suberin is a lipophilic biopolymer that acts as a protective barrier against excessive water loss in plants. In roots, the presence of suberin in the Casparian strip makes it distinct from the rest of the cell wall which mostly has lignin. The Casparian strip is present in root, apoplast, symplast.