Question

In angiosperms, root hairs arise from which one of the following regions of the root ?

• A. The region of meristematic activity
• B. The root cap zone
• C. The region of maturation
• D. The region of elongation

Hint:

Remember: Roots "grow" in the elongation zone, but they "drink" (absorb) through root hairs in the maturation zone.

Answer 1

The Correct Option is C

Step 1: Understanding the Question
The objective of this question is to identify the specific geographical and physiological zone of a plant root where specialized absorptive structures, known as root hairs, are produced. The root tip of an angiosperm is not a uniform structure; rather, it is divided into distinct zones based on the developmental state of the cells, starting from the protective tip and moving upwards toward the stem. Step 2: Key Formula or Approach
To solve this, we apply the principles of plant anatomy and developmental biology. Cells in a root undergo a linear progression: they are created in the meristem, they lengthen in the elongation zone, and they finally differentiate into specific functional tissues in the maturation zone. Root hairs are specialized unicellular extensions of the epidermal cells (epiblema) that only appear once the cell has stopped growing in length and has begun to mature. Step 3: Detailed Explanation
The Root Cap Zone: This is the thimble-like structure at the very apex of the root. Its primary role is to protect the underlying delicate tissues as the root pushes through the soil. It does not contain any epidermal hairs for absorption.
Region of Meristematic Activity: Located just a few millimeters above the root cap, this region consists of small, thin-walled cells with dense protoplasm. These cells are constantly dividing, meaning they are too developmentally "young" to form complex structures like root hairs.
Region of Elongation: The cells produced in the meristematic zone enter this region, where they undergo rapid enlargement and stretching. This zone is solely responsible for the root's growth in length and the cells here are still transitioning.
Region of Maturation: Proximal to the elongation zone, the cells attain their final size and undergo differentiation into primary tissues like xylem, phloem, and cortex.
Root Hair Formation: It is within this maturation zone that specific epidermal cells undergo morphogenesis to form fine, delicate, and thread-like structures called root hairs. These hairs are crucial for the plant as they dramatically increase the surface area available for the uptake of water and minerals from the soil.
Step 4: Final Answer
Because root hairs represent a differentiated state of epidermal cells, they arise exclusively from the region of maturation. Therefore, option (D) is the correct choice.