Question

Answer n brief
Sketch & label the following.
(i) Regions of root (ii) Typical leaf

Answer 1

Roots are the non-green,non-photosynthetic, positively geotropic and negatively phototropic underground part of a plant, without leaves, buds, nodes and internode.

A primary root has four longitudinal regions, namely from tip to base -the root apex, zone of elongation, zone of maturation, and the permanent region.

*Root apex is the extreme tip of the root with root cap.

*Elongation zone is the growing region just before the root tip. Here, meristematic cells undergo active division, differentiation and elongation.

*Maturation zone is the region before the elongation zone. Here the differentiated cells undergo maturation to form epidermal, cortical and vascular tissues. Root hairs are given out from this zone and so it is also called root hair zone.

Leaf

Leaves are the photosynthetic centres of plants, primarily concerned with photosynthesis, transpiration, and respiratory gas exchange. It develops from the leaf primordia of the apical meristem.

Typically, a leaf consists of four parts, namely the petiole(leaf stalk), lamina(leaf blade) with dorsal and the ventral sides, apex(leaf tip) and the leaf margin.

The leaf surface, that is continuous with the surface of the stem above the point of leaf insertion, is known as the upper, ventral, or adaxial side. The side is the lower, dorsal, or abaxial side. Leaf is composed of various tissues, which furnish various functions.