NEET Physics: Waves – NCERT Masterclass & 100 MCQ Quiz

ANATOMY OF FLOWERING PLANTS

NCERT Masterclass & NEET Biology Study Module

1. The Tissue Systems

Based on their structure and location, there are three types of tissue systems in plants:

A. Epidermal Tissue System

Forms the outermost covering of the whole plant body. Comprises epidermal cells, stomata, and epidermal appendages (trichomes and hairs).

• Epidermis: Usually single-layered, made of elongated, compactly arranged parenchymatous cells. Covered by a waxy thick layer called cuticle (prevents water loss). Cuticle is absent in roots.
• Stomata: Regulate transpiration and gaseous exchange. Each stoma consists of two guard cells.
  In Dicots: Guard cells are bean-shaped.
  In Monocots (Grasses): Guard cells are dumbbell-shaped.
• Epidermal Appendages: Root hairs are unicellular elongations that absorb water. Trichomes are usually multicellular stem hairs that prevent water loss due to transpiration.

B. The Ground Tissue System

All tissues except epidermis and vascular bundles constitute the ground tissue. It consists of simple tissues such as parenchyma, collenchyma, and sclerenchyma. In leaves, the ground tissue is called mesophyll (chloroplast-containing cells).

C. The Vascular Tissue System

Consists of complex tissues: xylem and phloem.

Types of Vascular Bundles:

• Radial: Xylem and phloem are arranged in an alternate manner on different radii. Found in Roots.
• Conjoint: Xylem and phloem are jointly situated along the same radius. Found in Stems and Leaves.
  • Conjoint Closed: Cambium is absent. Found in Monocot stems.
  • Conjoint Open: Cambium is present between phloem and xylem (capable of secondary growth). Found in Dicot stems.

2. Anatomy of Root

Exarch Xylem: Protoxylem lies towards periphery and metaxylem towards the centre (Found in ROOTS).

• Dicot Root: Epiblema (with root hairs), Cortex, Endodermis (has water-impermeable waxy Casparian strips made of suberin), Pericycle (initiation of lateral roots), mostly diarch to hexarch xylem bundles, and a small/inconspicuous pith.
• Monocot Root: Similar to dicot root, but has polyarch xylem bundles (more than six) and a large, well-developed pith. Secondary growth is entirely absent.

3. Anatomy of Stem

Endarch Xylem: Protoxylem lies towards the centre (pith) and metaxylem towards the periphery (Found in STEMS).

• Dicot Stem: Epidermis (with trichomes), Cortex (outer collenchymatous hypodermis), Endodermis (rich in starch grains, called starch sheath), Pericycle (semilunar patches of sclerenchyma). Vascular bundles are arranged in a Ring, conjoint, open, and with endarch protoxylem. Pith is large.
• Monocot Stem: Sclerenchymatous hypodermis, large number of scattered vascular bundles surrounded by a sclerenchymatous bundle sheath. Vascular bundles are conjoint and closed. Peripheral bundles are generally smaller than central ones. Water-containing cavities are present within the vascular bundles. Phloem parenchyma is absent.

4. Anatomy of Leaf

• Dicot (Dorsiventral) Leaf: Stomata are mainly on the lower (abaxial) epidermis. Mesophyll is differentiated into upper palisade parenchyma (elongated cells) and lower spongy parenchyma (loosely arranged with air spaces). Vascular bundles are surrounded by a bundle sheath.
• Monocot (Isobilateral) Leaf: Stomata are present on both surfaces. Mesophyll is not differentiated into palisade and spongy parenchyma. In grasses, certain adaxial epidermal cells modify into large, empty, colorless cells called Bulliform cells (help in minimizing water loss by curling the leaves).

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🚀 NEET PLANT ANATOMY MEGA QUIZ (100 MCQ)

Solve the 5 parts below to master Tissue Systems and Dicot vs Monocot Anatomy.

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