Question

Bundle sheath exfensions in a dicot leaf and in a monocot leaf are - and - respectively, (a) parenchymatous, colienchymatous (b) parenchymatous, sclerenchymatous (c) sclerenchymatous, parenchymatous (d) collenchymatous, selerenchymatous

Short answer

Bundle sheath extensions in a dicot leaf and in a monocot leaf are parenchymatous and sclerenchymatous respectively, making the correct option (b).

Step-by-step solution

Identify the Function of Bundle Sheath Extensions

Understand that bundle sheath extensions are support structures in leaves that are continuous with the vascular bundles. Their composition can differ between dicots and monocots.

Recall the Characteristics of Dicot and Monocot Leaves

Recall from botanical knowledge that dicots typically have a bundle sheath extension composed of parenchyma cells, which are thin-walled and not heavily lignified, while monocots often have a bundle sheath extension made up of sclerenchyma cells, which are thick-walled and heavily lignified.

Match the Leaf Types with Their Corresponding Bundle Sheath Extensions

Based on the characteristics of the bundle sheath extensions in dicots and monocots, match each type with the appropriate type of bundle sheath extensions.

Choose the Correct Option

After analyzing the options provided, choose the option that correctly matches the bundle sheath extension type to the leaf type for both dicots and monocots.

Key concepts

Dicot Leaf Anatomy

Understanding the anatomy of a dicot leaf is essential for students studying plant biology. Dicot leaves have a complex structure that provides both photosynthetic capabilities and means for gas exchange. At the microscopic level, you can see the distinct upper and lower epidermis layers protecting the leaf tissues beneath.

The mesophyll within is differentiated into palisade and spongy types, where the palisade mesophyll lies directly beneath the upper epidermis and contains tightly packed columnar cells rich in chloroplasts. This is where most of the photosynthesis occurs. The spongy mesophyll contains loosely arranged cells with air spaces to facilitate gas exchange.

Central to the leaf's structure are the vascular bundles, comprising xylem and phloem, which are responsible for water and nutrient transport. Importantly, dicot leaves feature bundle sheath extensions typically composed of parenchymatous tissue, providing support and facilitating the transportation of substances between the vascular bundles and other parts of the leaf. These characteristics distinguish dicot leaves and play a vital role in their functionality.

Monocot Leaf Anatomy

Monocot leaves have anatomical features that are quite distinct from those of dicots. In the world of botany, understanding these differences is crucial. Monocot leaves usually have parallel venation, with veins running side by side along the length of the leaf. This is in contrast to the net-like venation pattern seen in dicot leaves.

The internal structure of a monocot leaf is not differentiated into palisade and spongy mesophyll. Instead, they have evenly distributed mesophyll cells that serve both photosynthetic and gas exchange functions. Another significant difference is in the bundle sheath extensions, which are made of sclerenchymatous tissue in monocots. These cells are thick-walled and heavily lignified, providing greater strength and support to the leaf, a trait that can be particularly useful in high-wind environments or where water conservation is vital. Monocot leaf anatomy reflects the adaptations needed for survival in diverse ecological niches.

Plant Tissue Types

Plants comprise various tissue types, each specialized for different functions, which is a foundational concept in understanding plant anatomy and physiology. Firstly, we have dermal tissue, which includes the epidermis and protects against water loss, injury, and infection.

Vascular Tissue

It includes xylem and phloem, is pivotal for water and nutrient transport throughout the plant. Xylem moves water and soluble mineral nutrients from the roots to rest of the plant, while phloem distributes sugars, amino acids, and other organic products.

Ground Tissue

Consists of parenchyma, collenchyma, and sclerenchyma cells. Parenchyma cells are the most common, found throughout the plant and involved in photosynthesis, storage, and tissue repair. Collenchyma cells help support growing parts of the plant, characterized by their elongated shape and thickened cell walls. Lastly, sclerenchyma cells are responsible for the mechanical support of the plant, made distinctive by their very thick, lignified walls.

Understanding these plant tissue types aids in comprehending the function and makeup of various plant structures, including those found in the leaves of monocots and dicots.