Question

Dicot stem differs from dicot roots in :-

• A. Presence of cortex
• B. Absence of endodermis
• C. Absence of pericycle
• D. Position of protoxylem

Answer 1

The correct option is D Position of protoxylem

D. Position of protoxylem

Reason: In dicot stem, the outermost layer is called epidermis; the outer wall is covered with thick cuticle. The epidermis contains multicellular hairs and stomata. In dicot root, the outermost layer is called epiblema. It is containing intracellular hairs and thin walled cells. Here stomata and cuticle are absent. In dicot root, cortex is differentiated into general cortex and endodermis. On the other hand in dicot stem, cortex is differentiated into hypodermis, general cortex and endodermis. In dicot stem, pericycle is multilayered and it is composed of sclerenchyma or parenchyma or both. In dicot root, pericycle is single layered. It is composed of thin-walled parenchymatous cells. The first formed xylem is called protoxylem and it is position can be different is some dicot stem and dicot root.