Question

Starch sheath is another name of
A. Hypodermis
B. Endodermis
C. Casparian strip
D. None of the above

Answer 1

Hint: Starch sheath, as the name indicates, is a layer containing specialized cells that store a large number of starch grains. This layer is present inner to the cortex and outside to the pericycle of the dicot stem.

Complete step by step answer:
-Option (A) is incorrect. The hypodermis is made of 3-4 layers of collenchyma tissues. Its cells possess extra thickenings of cellulose in various regions i.e., at the angles, on the tangential walls, and near the intercellular spaces.
-Option (B) is correct. Endodermis in the dicot stem is a wavy layer and it lies inner to the cortex. The cells of this layer are barrel-shaped that do not enclose intercellular spaces and Casparian strips are generally absent. The cells of this layer are rich in starch grains as a food reserve. Therefore, the endodermis of the dicot stem is also known as the starch sheath.
-Option (C) is incorrect. Casparian strips are present in dicot roots and they are absent in the endodermis of dicot stems. As endodermis of the dicot stem but not the Casparian strip contains cells that are rich in starch grains therefore, endodermis is known as the starch sheath.
-Option (D) is incorrect. As option (B) is correct, therefore ‘none of the above options’ cannot be correct.

Hence, the correct option is (B).

Note: The starch sheath is another name of the endodermis of the dicot stem. This layer contains barrel shaped cells that are rich in starch grains as a food reserve. Endodermis helps in regulating the movement of water, ions, and hormones into and out of the vascular system. It may also be involved in the perception of gravity and protecting the plants from toxins moving into the vascular system.