Problem 45 - Objective Biology for NEET

Question

Which portion of the root absorbs both water and minerals? (a) Terminal portion of roots (b) Zone of cell elongation (c) Zone of cell formation (d) Zone of cell differentiation

Step-by-Step Solution

Answer

(d) Zone of cell differentiation

Step 1: Understand root structure

Roots are divided into different zones based on their functions. The terminal portion of roots mainly contains root cap which protects the growing tip in soil. The zone of cell formation is where cells divide, known as meristematic zone. The zone of cell elongation is where the cells begin to enlarge. And the zone of cell differentiation is where the cells mature and take on their role in the plant.

Step 2: Identify the function of each zone

Each of the zones of the root has a unique function. The terminal portion, while important for the stability and movement of the root in the ground, is not the primary spot for absorption. The zone of cell elongation, as well as zone of cell formation, mainly deal with cell growth, not absorption. The zone of cell differentiation, on the other hand, is where cells mature and specialize, and it includes the cortex, which is the main area for absorption in roots.

Step 3: Determine the answer

Considering the functions of each zone, we can deduce that the Zone of Cell Differentiation absorbs both water and minerals. Therefore, the answer is (d) Zone of cell differentiation.

Key Concepts

Zones of Root Growth

Roots have different zones which perform various roles essential for plant life. Starting from the tip, the root is composed of several distinct regions:

• Root Cap: This is the very terminal portion which protects the growing tip from damage as it pushes through the soil.
• Zone of Cell Formation: Also known as the meristematic zone, this is where rapid cell division takes place allowing roots to grow.
• Zone of Cell Elongation: Here, the newly formed cells begin to increase in size. This elongation pushes the root further into the ground.
• Zone of Cell Differentiation: In this zone, cells mature and undergo specialization to acquire specific roles such as forming vascular tissues.

Each of these zones has its unique function but works together to ensure the root grows properly and fulfills its primary responsibilities.

Cell Differentiation in Roots

Cell differentiation is a critical process in the zones of root growth. It is especially vital in the zone of cell differentiation, where cells specialize and take on unique functions.

• Specialized Tissues: During differentiation, cells form specialized structures like the xylem and phloem, essential for transporting water, nutrients, and food.
• The Cortex: Cells here form a thick layer that functions as a pathway for water and mineral absorption from the soil to the xylem.
• Root Hairs: Tiny extensions that increase the surface area for absorption, allowing efficient uptake of water and minerals.

This maturation process enables the root to carry out its role in providing nutrients to the rest of the plant effectively.

Water and Mineral Uptake in Plants

Plants need both water and minerals to survive, and the root system is specially adapted for this task through a process called root absorption.

• Water Uptake: Occurs mainly through osmosis; water moves from the soil into the root hairs and then passes through the cortex to reach the plant's vascular system.
• Mineral Uptake: Minerals are absorbed by active transport, which requires energy. This process allows plants to intake essential nutrients against a concentration gradient.
• Role of Root Hairs: These fine extensions maximize contact with soil, enhancing the plant's ability to absorb nutrients efficiently.

This absorption mechanism is crucial for plant growth, affecting processes such as photosynthesis, respiration, and overall development.