Botany lecture notes

Sclerenchyma: Structure, Classification and Functions with PPT


sclerenchymatous tissue ppt

Sclerenchyma
(Structure, Types and Functions of Sclerenchymatous Cells in Plants)

What are Sclerenchymatous Cells?

Ø  Sclerenchyma is a simple permanent tissue in plants.

Ø  Sclerenchymatous cells are dead at their maturity.

Ø  Cells do not have protoplast when they completely developed.

Ø  They have thick secondary cell wall.

Ø  The secondary cell wall is lignified and very hard.

Ø  Most of the sclerenchymatous cells show intrusive growth.

Different Types of Sclerenchymatous Cells in Plants:

Ø  Based on size, two types of sclerenchyma are described.

  (I).   Sclereids

(II).    Fibres

(I). Sclereids:

Ø  Sclereids are short sclerenchymatous cells.

Ø  They are also called as stone cells.

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Botany lecture notes

Collenchyma Cells in Plants: Structure, Classification and Functions with PPT

Functions of collechyma

Collenchyma
(Structure, Types and Functions of Collenchymatous Cells in Plants)

What is collenchyma?

Ø  Collenchyma is a simple permanent tissue in plants.

Ø  They are living cells with prominent nucleus and all the cell organelles.

Ø  Each collenchymatous cell is with a large and prominent vacuole in the centre.

Ø  The vacuole is filled with many secondary metabolites.

Ø  Unlike parenchyma, the collenchyma cells possess thick primary cell wall.

Ø  Thick walls are NOT lignified.

Ø  The thick wall is due to the deposition of hemicellulose and pectin along with cellulose.

Ø  Wall thickening in collenchyma is greatly affected by the extent of mechanical stress.

Ø  A plant part which in severe stress or motion due to high wind are more likely to possess more thickened collenchyma.

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Zoology lecture notes and study materials

Epithelial Tissue: (Types, Structure, Functions & Examples)


classification of epithelial cells

Classification of Epithelial Tissue in Animals

Epithelial Tissue: (Structure, Classification and Functions)
(Structure Classification and Functions of Simple and Compound Epithelium)

What is Epithelium?

Ø  Epithelium is a tissue system in animals.

Ø  Epithelium constitutes the outer layer of body surfaces, linings of the alimentary canal and the walls of hollow structures.

Ø  It covers the internal or external surfaces of the body.

Ø  Epithelial cells are held together by carbohydrate based cementing materials.

Ø  They also possess special junctions between the cells.

Ø  The bottom layer of epithelium is rest on the basement membrane.

Ø  The basement membrane composed of a network of fibrous proteins particularly rich in collagens.

Ø  Epithelial layers are NOT provided with any blood vessels.

Ø  The cells of the epithelium obtain nutrients and oxygen by diffusion from the lymphatic vessels.

Ø  Nerve endings occur in the epithelial tissues for receiving stimuli.

What are the Functions of Epithelial Tissue?

Ø  Epithelium provides protection to the underlying structures.

Ø  Protect organs from injuries by external agencies or pressure.

Ø  Prevent infection by microorganisms.

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Botany lecture notes

Difference between Parenchyma and Collenchyma: A Comparison Table


collenchyma vs parenchyma

Parenchyma vs Collenchyma
(Similarities and Differences between Parenchyma and Collenchyma)

Parenchyma and Collenchyma are the Simple tissue System in Plants. The present post describes the similarities and differences between PARENCHYMA and COLLENCHYMA.

Similarities between Parenchyma and Collenchyma

Ø  Both parenchyma and collenchyma are simple permanent tissues in the plants.

Ø  Both are differentiated cells.

Ø  Both are living cells with primary cell wall.

Ø  Both cells possess cytoplasm and cell organelles including the nucleus.

Ø  Both are the components of ground tissue system in plants.

Ø  Both cells can do photosynthesis if chloroplasts are present in them.

Ø  Both can store food materials as starch grains.

Ø  Pits are absent in the cell wall of both parenchyma and collenchyma.

Ø  Plasmodesmatal connections between cells occur in both cells.

Differences between Parenchyma and Collenchyma

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Botany lecture notes

What are the Characteristics of Meristems & Meristematic Cells?

Mitosis (261 14) Pressed; root meristem of onion (cells in prophase, anaphase)

Meristematic Cells of Root Apex Showing Cell Division (source wikipedia)

What are Meristems?

Meristem is a group of plant cells that remain in a continuous state of division. It is a tissue system in plants called meristematic tissue. The term meristem was proposed by Karl Nägeli from a Greek word ‘merizein’ which means ‘to divide’. The meristem composed of rapidly dividing undifferentiated mass of cells. Meristems are usually found in the growing region of plant organs such as shoot apex and root apex. Usually meristem originates from the embryonic cells. The primary function of meristem is to assist in plant growth and development. Meristematic cells are characteristically different from other differentiated cells in terms of many aspects. This post describes the characteristic features of meristematic cells in plants.

What are Characteristics of Meristems / Meristematic Tissues?

§.  Meristem composed of rapidly dividing cells

§.  Usually situated at the growing apex of plant parts (root apex or shoot apex)

§.  Meristematic cells are undifferentiated

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