Question

Typically, vascular tissue is organized as in stems and as \(\quad\) in roots. a. multiple vascular bundles; one vascular cylinder b. one vascular bundle; multiple vascular cylinders c. one vascular cylinder; multiple vascular bundles d. multiple vascular cylinders; one vascular bundle

Short answer

Option (a) is correct: stems have multiple vascular bundles, and roots have one vascular cylinder.

Step-by-step solution

Understand the Question

The exercise is asking about the arrangement of vascular tissues in plant structures, specifically comparing stems to roots. We need to identify how vascular tissue is typically organized in both stems and roots.

Identify Typical Vascular Arrangement in Stems

Stems usually feature multiple vascular bundles. These bundles consist of xylem and phloem tissues and are dispersed throughout the stem, sometimes forming a ring in dicots.

Identify Typical Vascular Arrangement in Roots

Roots typically have one vascular cylinder. This structure is central within the root and contains the necessary vascular tissues to transport water and nutrients.

Match the Descriptions to the Options Given

Based on our understanding: stems have multiple vascular bundles, and roots have one vascular cylinder. Now, we need to find the option that matches this description.

Select the Correct Option

Option (a) 'multiple vascular bundles; one vascular cylinder' correctly describes the vascular arrangements in stems and roots, respectively.

Key concepts

Vascular Bundles

Vascular bundles are like transportation highways within plant stems. They contain two main types of tissue - xylem and phloem - which are crucial for moving water, nutrients, and food throughout the plant.
Think of

• Xylem: This tissue carries water and dissolved minerals from the roots upwards to other parts of the plant.
• Phloem: Responsible for transporting the food produced by photosynthesis in the leaves down to the roots and other growing regions.

In many plant stems, especially in dicots, vascular bundles are organized in a ring. This arrangement provides strength and support to the plant, helping it stand erect and withstand various environmental stresses.

Vascular Cylinder

The vascular cylinder, often known as the stele, is a central part of a root. Unlike the dispersed bundles in stems, the vascular tissues in roots are concentrated in this central cylinder.
Within the vascular cylinder, you will find:

• Xylem: Arranged in a star-like pattern, it is primarily responsible for moving water and nutrients upwards.
• Phloem: Positioned between the arms of the xylem, it transports sugars from photosynthesis.

The centralized arrangement in a single cylinder supports efficient transport and strengthens the root as it penetrates the soil. This structure plays a vital role in the root’s ability to anchor the plant and facilitate the uptake of water and essential minerals.

Stem Anatomy

Understanding stem anatomy is crucial for recognizing their role in plant survival and efficiency. Stems display several distinct features:

• Nodes: Points on a stem where leaves, branches, or flowers are attached. They play a critical role in the growth and branching out of the plant.
• Internodes: The stem segments between nodes, which determine the plant height and spacing of leaves.
• Cuticle: A waxy layer covering the stem that protects against water loss and pathogen entry.

Moreover, the presence of vascular bundles organized in specific patterns not only aids in the transport of nutrients and water but also provides mechanical support, allowing stems to handle environmental stresses.

Root Anatomy

The anatomy of plant roots is specialized for support, nutrient absorption, and anchoring the plant. It includes several key structures:

• Root Cap: A protective structure that covers the root tip, safeguarding new cell growth as the root pushes through soil.
• Zone of Cell Division: Located just behind the root cap, where cells rapidly divide, contributing to root growth.
• Zone of Elongation: Follows the zone of cell division and is where cells grow larger and the root stretches out further into the soil.
• Root Hairs: Tiny extensions that increase the surface area for absorption, efficiently taking up water and nutrients from the soil.

Together, these structures ensure roots can effectively anchor the plant, absorb vital nutrients, and facilitate growth by continuously penetrating the soil.