Question

In root-system transition region the vascular bundles are
(a) Radial
(b) Conjoint
(c) Collateral
(d) None

Answer 1

Hint: In vascular plants, the roots are the organs of a plant that mostly lie beneath the surface of the soil. Roots also can be aerial or aerating, that is, growing up above the bottom or especially above water.

Complete answer:
In higher plant roots and shoots form an endless axial structure. The straightforward sort of axial structure is exhibited in Psilophytales. In higher plants, the differentiated plant body into root, stem, and leaf is considered an evolutionary specialization of straightforward axial structure.

The differentiation of root and stem is initiated within the embryo axis. An embryo is formed from one or two cotyledons. Towards the upper end just above the insertion of the cotyledon, there occurs the primordial of shoot-plumule. The portion between the insertion of cotyledon and plumule is that of the epicotyl (epi means above).

Towards the lower end slightly below the insertion of cotyledon there occurs the primordial root- the radicle. The portion between the insertion of cotyledon and radicle is hypocotyl (hypo means below). Radicle and plumule form an endless axial structure with the intervening tissues of hypocotyl and epicotyl. The radicle grows below to take root. Plumule grows above to make a shot.

So, the correct answer is ‘Radial’.

Note: The vascular tissue in the root is radial (xylem and phloem arranged separately in different radii) whereas in the stem is conjoint (xylem and phloem are arranged together in the same radii as vascular bundles). Root-stem transition zone, the region where the vascular structure of the root and the stem meets and merges together.