Problem 35 - Objective Biology for NEET

Question

Ascent of mineral is mainly due to (a) Xylem (b) Phloem (c) Pericycle (d) Cortex

Step-by-Step Solution

Answer

The ascent of minerals is mainly due to the Xylem.

Step 1: Understanding Plant Anatomy

In plant anatomy, the Xylem is the tissue responsible for the upward transport of water and dissolved minerals from the roots to other parts of the plant. The phloem, on the other hand, is involved in the transport of nutrients, specifically sugars produced by photosynthesis, to all parts of the plant.

Step 2: Determining the Role of Pericycle and Cortex

The pericycle is involved in the formation of lateral roots and is not linked to the ascent of minerals. The cortex, composed of unspecialized cells and tissues, does aid in the transport of fluids and nutrients through the plant but it does not primarily contribute to the upward transport of minerals.

Step 3: Final choice

After understanding the roles of the options, it is clear that the Xylem has the main role in the upward transport of water and minerals from the roots to other parts of the plant.

Key Concepts

Plant Anatomy

Plant anatomy is the study of the internal structure of plants. Plants have various tissues and systems that all play distinct roles in their growth and survival. Two essential components of plant anatomy are the xylem and phloem, which are responsible for the transportation of fluids and nutrients.

Xylem is like a network of waterways that carries water and minerals absorbed from the roots upwards to the rest of the plant. This system is critical for plant survival as it ensures that every part of the plant receives the necessary hydration to perform photosynthesis and other vital processes.

• Xylem: Transports water and dissolved minerals.
• Phloem: Carries nutrients, primarily sugars.

Understanding plant anatomy helps researchers and students alike to comprehend how plants grow and adapt to their environments.

Phloem Function

The phloem plays a pivotal role in the transport of nutrients across the plant. Unlike xylem, which only moves substances in one direction (upward), the phloem can transport sugars and other metabolic products in multiple directions.

This bidirectional movement is known as "translocation" and is essential for distributing the products of photosynthesis from the leaves (where they are produced) to parts of the plant that do not perform photosynthesis, such as roots and flowers. The process involves specialized cells within the phloem that facilitate the movement of these vital nutrients.

• Sugar Transport: Phloem moves sugars to wherever energy is needed.
• Flexible Movement: Allows nutrients to flow to growing parts of the plant.

The phloem function ensures that the plant maintains its energy balance and supports growth and development.

Pericycle Role

Within the plant root, the pericycle plays an important but less well-known role. It is a layer of cells located just inside the endodermis, which surrounds the vascular tissue in the roots. The primary role of the pericycle is in lateral root formation, which is crucial for increasing the plant’s root system.

Though not directly involved in the upward transport of minerals, the pericycle supports plant growth by ensuring a robust and expansive root network that can access water and nutrients deeper in the soil.

• Lateral Roots: Pericycle cells initiate the growth of new roots.
• Structural Support: Provides a base for expanding the root system.

The pericycle's function supports overall plant stability and nutrient access, which indirectly impacts mineral uptake efficiency.

Cortex Function

The cortex is a versatile plant tissue found in roots and stems, acting as a storage and transport system for nutrients within the plant. It consists of loosely packed cells that create passages for nutrients to move between vascular tissues and other parts of the plant.

While the cortex is not primarily responsible for mineral transport like the xylem, it plays a supportive role by aiding in internal nutrient distribution and serving as a storage depot for starches and other substances. This helps ensure that essential nutrients are available as needed across different parts of the plant.

• Storage: Holds sugars and nutrients for later use.
• Nutrient Movement: Supports movement from one part of the plant to another.

The cortex, therefore, indirectly assists in the plant's nutrient management while providing structural flexibility.