Question

Polyarch and exarch vascular bundles are the characteristics of
a. Dicot stem
b. Dicot root
c. Monocot stem
d. Monocot root

Answer 1

Hint: In order to distinguish between monocots and dicots, the arrangement of vascular bundles in stems whereas in roots, vascular cambium and secondary growth through concentrated annual rings development in stems and roots is observed.

Complete answer:
> Option A is incorrect. Dicot stem vascular bundles, arranged in the shape of a broken chain, are eight in size. The conjoint, collateral and free vascular bundles. Xylem is on the inner side, and the outer surface of the phloem. Xylem is termed endarch. In a pith area, the dicot stems have bundles in a ring that surround parenchyma cells.

> Option B is incorrect. The vascular bundles of the dicot root are defined as radial and tetrarch. Each xylem and phloem occur alternately in four bundles (xylem in the root centre and phloem outside the xylem). It defines Xylem is exarch.

> Option C is incorrect. Vascular bundles of monocot stems are conjoint, collateral and closed. Xylem is their research. Only two protoxylem vessels and two metaxylem vessels are present in each packet. In monocots there is no area with a pith.

> Option D is correct. Monocot root vascular bundles (arranged in a ring) are radial in structure. Eight bundles of xylem and phloem are in each. The condition is therefore defined as being polyarchic. In them, Xylem is defined as being exarch.

So, the correct answer is Option D.

Note: A vascular bundle is an important part of the vascular plant transport network. The transport takes place through xylem and the phloem. Both these tissues are found in a vascular bundle, which may also contain protective and supporting tissues. One of the main differences between the stems & roots of monocots and dicots is the arrangement of vascular bundles and the secondary growth.