Question

Choose the correct answers from the alternatives given.
One important difference between the anatomy and physiology of roots and leaves is that
a. Unlike roots, the xylem vessels in leaves normally transport sap in both directions
b. A waxy cuticle covers most leaves but is absent in roots
c. Leaves, but not roots, have ground tissue consisting mainly of parenchyma cells
d. Phloem always conducts sap away from leaves and toward roots

Answer 1

Root Anatomy refers to the structure of the roots whereas Root Physiology refers to the functions of the roots. Roots help to draw water, minerals and nutrients from the soil. Leaves are the food factory of the plant. They prepare food for the plant from the minerals and nutrients delivered by the roots through the stem.

Complete answer:
In order to know the difference, it is important to know the structure of both roots and leaves.

Structure of Root: The tip of the root is formed of apical meristem which is a meristematic tissue. It helps in elongation of the roots. The outer covering of the roots is of hair-like projections known as the root hair which help in absorbing maximum amounts of water and nutrients. The xylem and phloem are the water and food transportation vascular bundles. The roots have parenchyma cells as well.

Structure of Leaves: The leaves are made up of a midrib, a petiole, an edge and veins. The large area of the leaf is covered with a waxy layer of cuticle. The veins have xylem and phloem bundles for transportation of water and minerals to and from leaves.

From the options provided we infer that one important difference between the anatomy and physiology of roots and leaves is that a waxy cuticle covers most of the leaves but is absent in roots.

Hence, the correct answer is option (B).

Note: The cuticle which is present on the surface area of the leaf prevents excessive loss of water from the surface of the leaf. Leaves lose water due to the transpiration process. Roots do not undergo transpiration as they stay immersed in the soil, away from exposure to sunlight. Therefore, they do not require a cuticle.