Assertion (A): Taproot system is fundamentally different from the fibrous root system in terms of embryonic origin. Reason (R): Taproots develop as a direct elongation of the radicle, whereas fibrous roots originate from the base of the stem after the primary root is short-lived.
The primary root in dicotyledonous plants is a direct elongation of the radicle. In monocotyledonous plants, the primary root is short-lived and replaced by multiple roots originating from the base of the stem (fibrous root system). This makes their embryonic developmental path and origin structurally and logically distinct.
Question 102 of 300
📘 CLASS XI
Assertion (A): Roots arising in the banyan tree and Monstera are termed adventitious roots. Reason (R): Adventitious roots are defined as those that develop from parts of the plant other than the radicle.
By definition, adventitious roots arise from any part of the plant body other than the embryonal radicle. Since the supporting roots of the banyan tree and roots of Monstera arise from branches or stem nodes, they are adventitious, and the reason provides the standard botanical definition for this term.
Question 103 of 300
📘 CLASS XI
Statement I: The synthesis of plant growth regulators is a physiological function performed by the root system. Statement II: Storing reserve food material and providing proper anchorage are purely mechanical processes that occur without metabolic expenditure by root tissues. Select the correct option:
Statement I is correct because the synthesis of plant growth regulators is an established physiological function of roots. Statement II is incorrect because storing food and maintaining root tissue for anchorage involve metabolically active processes, cellular respiration, and active transport; they are not purely mechanical processes devoid of metabolic activity.
Question 104 of 300
📘 CLASS XI
Why is the region of maturation considered the physiologically most active zone for water and mineral absorption, rather than the region of elongation?
The root hairs are delicate, thread-like structures formed by some of the epidermal cells specifically in the region of maturation. These root hairs are the primary structures for absorbing water and minerals, making this zone the most active for absorption. Cells in the elongation zone are responsible for lengthening the root, not absorption.
Question 105 of 300
📘 CLASS XI
Consider the following sequence of zones in a root-tip from apex to base (proximal direction): $$\text{Root Cap} \longrightarrow \text{Zone X} \longrightarrow \text{Zone Y} \longrightarrow \text{Zone Z}$$ What are the characteristic features of the cells in Zone X?
Zone X represents the region of meristematic activity, which lies a few millimeters above the root cap. The cells of this region are characterized by being small, thin-walled, having dense protoplasm, and dividing repeatedly.
Question 106 of 300
📘 CLASS XI
Assertion (A): If a root cap is artificially removed, the root-tip can still successfully navigate through compact soil without damage to its meristem. Reason (R): The root cap is purely an anatomical vestige with no active protective or mechanical role in root growth.
Both statements are false. The root cap is a thimble-like structure that actively protects the tender apex of the root as it makes its way through the soil. Removing it exposes the delicate apical meristem to friction and mechanical damage, hindering navigation through soil. Thus, it is not a vestige.
Question 107 of 300
📘 CLASS XI
Which of the following statements logically explains why a plant like mustard has a tap root system while wheat has a fibrous root system?
In dicotyledonous plants like mustard, elongation of the radicle directly leads to the taproot system. In monocotyledonous plants like wheat, the primary root is transient or short-lived, replaced by numerous roots arising from the base of the stem, forming the fibrous root system.
Question 108 of 300
📘 CLASS XI
Statement I: Root hairs originate from the cells of the region of elongation as cellular protrusions. Statement II: Root apical meristem cells have dense protoplasm and very thin cell walls to facilitate rapid cell division. Select the correct option:
Statement I is incorrect because root hairs originate from the epidermal cells of the region of maturation (proximal to the elongation zone), not the region of elongation. Statement II is correct because meristematic cells are small, thin-walled, and have dense protoplasm to support active mitotic division.
Question 109 of 300
📘 CLASS XI
If a plant has leaves with parallel venation and seeds with a single cotyledon, what type of root system is it most likely to possess?
Parallel venation and single-cotyledon seeds are characteristics of monocotyledons. The characteristic root system of most monocotyledonous plants (like wheat) is the fibrous root system.
Question 110 of 300
📘 CLASS XI
Assertion (A): The region of elongation is primarily responsible for the rapid increase in root length. Reason (R): The cells proximal to the meristematic region undergo rapid enlargement, elongation, and vacuolation.
The cells in the region of elongation (which are proximal to the meristematic region) undergo rapid elongation and enlargement, directly contributing to the root's growth in length.
