Question

I. Cortex is made up of several layers of thin-walled parenchyma cells with intercellular spaces. II. Endoderm is made up of single layer of barrel-shaped cells without any intercellular spaces. III. Few layers of thick-walled parenchymatous cell forms pericycle. IV. Pith is small or inconspicuous. V. Conjuctive tissue present is 2 to 4 xylem and phloem patches. (a) Dicot root (b) Dicot stem (c) Monocot root (d) Monocot stem

Short answer

The correct answer is (a) Dicot root. This structure matches all sentences I.-V.

Step-by-step solution

Characterization of Plant Structure Features

The first step is to understand what the given features characterize. I. Cortex made of several layers of thin-walled parenchyma cells with intercellular spaces marks the features of both dicot and monocot stems.II. Endoderm made up of a single layer of barrel-shaped cells with no intercellular spaces is a feature of both dicot and monocot roots. III. Few layers of thick-walled parenchymatous cells form the pericycle, a typical trait of both dicot and monocot roots. IV. Small or inconspicuous pith is a trait of dicot roots primarily, but also present in monocot stems. V. Conjunctive tissue present is 2 to 4 xylem and phloem patches is characteristic of dicot roots.

Choosing the Appropriate Option

The next step is to select the option that includes all the mentioned features. Standing out amongst all, 'Dicot root' fulfils all the characteristics mentioned. It has a cortex, endodermis, a pericycle made of parenchyma cells, and a possibly small pith, and conjunctive tissue with 2 to 4 xylem and phloem patches.

Key concepts

Dicot Root Structure

Understandably, the structure of a dicot root is complex, yet fascinating. The dicot root is typically found in plants that produce seeds with two embryonic leaves, or cotyledons. Fundamentally, root structures serve the plant by anchoring it to the soil, absorbing water and minerals, and sometimes storing food. In dicot roots, a key feature is the presence of a cortex, which consists of several layers of thin-walled parenchyma cells. These cells often contain intercellular spaces, allowing for the transport of gases within the root.

At the center of the action, we find the vascular cylinder formed by the pericycle – a layer of thick-walled parenchymatous cells. This layer is significant for lateral root development. Additionally, the endodermis, which is a boundary layer of barrel-shaped cells, acts like a gatekeeper, regulating the movement of substances into the vascular system of the plant. What's noteworthy is the presence of a small or inconspicuous pith, often seen in dicot roots, indicating its minor role in storage or transport of nutrients.

Plant Tissue Types

Delving deeper into plants, we discover a fascinating variety of tissues, each with a distinct role. Plant tissues can be broadly categorized into three types: dermal, vascular, and ground tissue.

The dermal tissue encompasses the outer protective layer, including the epidermis, which acts as a barrier against pathogens and helps in water conservation. Vascular tissue, on the other hand, is crucial for transport. It consists of the xylem and phloem – xylem carries water and dissolved minerals upwards from the roots, whereas phloem distributes sugars and other metabolic products downward from the leaves. Lastly, the ground tissue fills the spaces in between, comprising parenchyma, collenchyma, and sclerenchyma cells, and is responsible for functions such as storage, support, and photosynthesis.

Understanding these tissue types helps clarify how plants maintain their essential functions and structural integrity, ensuring efficient nutrient delivery and growth.

Xylem and Phloem Distribution

The circulatory system of a plant is an elegant network that parallels the complexity found in animal systems. Xylem and phloem are the two main types of vascular tissue, functioning as the lifelines of the plant.

The xylem's primary role is to transport water and dissolved minerals absorbed from the soil up to the leaves. Typically, this transportation is against gravity, emphasizing the need for a robust structure. Thus, xylem vessels are characterized by their thick, lignified walls.

Conversely, the phloem is the tissue responsible for translocating organic nutrients, such as the sugars produced during photosynthesis, from the leaves to other parts of the plant that need them. The distribution of xylem and phloem is particularly interesting in dicot roots, where they are organized into 'patches' within the vascular cylinder - usually observed as 2 to 4 xylem and phloem patches, a distinct feature when comparing dicots to monocots.

This distribution plays a pivotal role in defining the functionality and resilience of the plant's vascular system, and ultimately, its survival.