Problem 156 - Objective Biology for NEET

Question

Well-developed pith is found in (a) Monocot stem and dicot root (b) Monocot and dicot stems (c) Dicot stem and dicot root (d) Dicot stem and monocot root

Step-by-Step Solution

Answer

The correct answer is (c) Dicot stem and dicot root.

Step 1: Analyze Options

In order to solve this exercise, knowledge about the structure of the plants is necessary. Pith is the central tissue in a plant stem or root, surrounded by vascular tissue. The pith is most commonly found in dicots and not in monocots. So, rule out any options that suggest pith in monocot stems or roots.

Step 2: Determine the Correct Option

When analysing the options, option (a) and option (d) both include monocot, so they can be discarded. This leaves options (b) and (c). Considering that the pith is not commonly found in a dicot root as well, option (b) can also be discarded. This leaves us with option (c) as the correct choice.

Key Concepts

Pith

The pith, often called the medulla, is a soft and spongy tissue located at the center of plant stems and sometimes roots. Its primary role is to store nutrients, helping sustain the plant. The pith is most prominent in the stem of dicotyledons (dicots), which are flowering plants with two seed leaves. In these plants, it acts as a storage area for vital substances like water and carbohydrates.
In contrast, monocotyledons (monocots), which have one seed leaf, rarely develop a well-defined pith. This difference is key to identifying and understanding various plant structures.
When studying plant anatomy, it's essential to know that:

• Pith cells can be living or dead at maturity, depending on the plant species and its location in the stem.
• Some plants' pith might degrade as they mature, creating a hollow stem.

Being aware of these variations helps in recognizing and classifying plant species based on their internal structures.

Monocot Stem

The monocot stem is an integral part of monocotyledonous plants, such as grasses and lilies. Structurally, it differs from the dicot stem primarily due to its scattered vascular bundles.
Monocot stems are often characterized by:

• The absence of a distinct pith. Monocots typically don't have a clearly defined central pith, as their internal structure doesn't concentric arrangements typical in dicots.
• Scattered vascular bundles, without a specific arrangement. This is a crucial distinction that helps identify monocots from other plant groups.

Understanding these features gives an insight into how monocots grow and function, especially under different environmental conditions.

Dicot Stem

The dicot stem is notable in the world of plant anatomy. These stems belong to dicotyledons, like roses and oaks, which have two seed leaves. They are structurally distinct from monocot stems for several reasons.
Key features of dicot stems include:

• Presence of a well-defined pith at the core. The pith in dicot stems is typically very prominent and serves as a storage reservoir.
• Vascular bundles arranged in a circle, creating a ringed pattern. This arrangement helps with more efficient transport of nutrients and water.

These characteristics are crucial for their structural integrity and their ability to support larger and more complex plant forms. Recognizing the presence of a pronounced pith helps differentiate dicots from their monocot counterparts.

Dicot Root

When examining dicot roots, one might notice that they diverge slightly from the common features found in dicot stems. While dicot roots are part of the two-seed leaf plants, their internal structure is adapted for anchorage and nutrient absorption.
Important aspects of dicot roots include:

• Typically, they have a central core of xylem in the root, designed to efficiently transport water upwards from the soil.
• They generally lack a prominent pith like that found in dicot stems. Instead, they are more focused on structural strength and nutrient absorption.

Due to these variations, dicot roots can effectively support the plant's needs, differing from stems, yet still a critical component of the plant's anatomy. Understanding these distinctions is crucial for students exploring plant life and their functional roles.