Changes

===Notes for teachers===

===Notes for teachers===

Permanent tissues in plants are divided into simple permanent and complex permanent tissues.Simple permanent tissues are again divided into three types.

Permanent tissues in plants are divided into simple permanent and complex permanent tissues.Simple permanent tissues are again divided into three types.

They are Parenchyma,Collenchyma and Sclerenchyma.<br>

They are '''Parenchyma,Collenchyma and Sclerenchyma'''.<br>

PARENCHYMA TISSUE:<br>

'''PARENCHYMA TISSUE''':<br>

Cells formed by meristematic tissue take up a specific role and lose the ability to divide. As a result,they form a permanent tissue. This processof taking up a permanent shape,size and function is called differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissue.<br>

Cells formed by meristematic tissue take up a specific role and lose the ability to divide. As a result,they form a permanent tissue. This processof taking up a permanent shape,size and function is called differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissue.<br>

Parenchyma, in plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. Parenchyma may be compact or have extensive spaces between the cells. It is often called ground, or fundamental, tissue and makes up the mesophyll (internal layers) of leaves and the cortex (outer layers) and pith (innermost layers) of stems and roots; it also forms the soft tissues of fruits. Cells of this type are also contained in xylem and phloem as transfer cells and, with both xylem and phloem as bundle sheaths, the cells that surround the vascular strands.<br>

Parenchyma, in plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. Parenchyma may be compact or have extensive spaces between the cells. It is often called ground, or fundamental, tissue and makes up the mesophyll (internal layers) of leaves and the cortex (outer layers) and pith (innermost layers) of stems and roots; it also forms the soft tissues of fruits. Cells of this type are also contained in xylem and phloem as transfer cells and, with both xylem and phloem as bundle sheaths, the cells that surround the vascular strands.<br>

http://www.mhhe.com/biosci/pae/botany/histology/images/parench.jpg<br>

http://www.mhhe.com/biosci/pae/botany/histology/images/parench.jpg

Parenchyma tissue<br>

'''Parenchyma tissue'''

Parenchyma tissue is composed of loosely packed thin wall cells so that large spaces between cells(intercellular spaces) are found in this tissue. This tissue provides support to plants and also stores food. In some situations, it contains chlorophyll and performs photosynthesis, and then it is called

Parenchyma tissue is composed of loosely packed thin wall cells so that large spaces between cells(intercellular spaces) are found in this tissue. This tissue provides support to plants and also stores food. In some situations, it contains chlorophyll and performs photosynthesis, and then it is called

chlorenchyma. In aquatic plants like pistia and lotus, large air cavities are present in parenchyma to give buoyancy to the plants to help them float.Such a parenchyma type is called aerenchyma. The parenchyma of stems and roots also stores nutrients and water.<br>

'''chlorenchyma'''. In aquatic plants like pistia and lotus, large air cavities are present in parenchyma to give buoyancy to the plants to help them float.Such a parenchyma type is called '''aerenchyma'''. The parenchyma of stems and roots also stores nutrients and water.<br>

COLLENCHYMA TISSUE:<br>

'''COLLENCHYMA TISSUE''':<br>

The flexibility in plants is due to another permanent tissue, collenchyma. It allows easy bending in various parts of a plant (leaf,stem,petiole) without breaking. It also provides mechanical support to plants. We can find this tissue in leaf stalks below the epidermis.The cells of this tissue are living, elongated and irregularly thickened at the corners. There is very little intercellular space.The cell wall is made up of cellulose and pectin.<br>

The flexibility in plants is due to another permanent tissue, collenchyma. It allows easy bending in various parts of a plant (leaf,stem,petiole) without breaking. It also provides mechanical support to plants. We can find this tissue in leaf stalks below the epidermis.The cells of this tissue are living, elongated and irregularly thickened at the corners. There is very little intercellular space.The cell wall is made up of cellulose and pectin.<br>

http://everythingscience.co.za/lifesciences/grade-10/04-plant-and-animal-tissues/images/6d29e2ef912af90a6d0451f417787577.png<br>

http://everythingscience.co.za/lifesciences/grade-10/04-plant-and-animal-tissues/images/6d29e2ef912af90a6d0451f417787577.png<br>

http://images.tutorvista.com/content/tissues-plants-animals/collenchyma-cells.jpeg

http://images.tutorvista.com/content/tissues-plants-animals/collenchyma-cells.jpeg

SCLERENCHYMA:<br>

'''SCLERENCHYMA''':<br>

Sclerenchyma is the tissue which makes the plant hard and stiff. We have seen the husk of a coconut. It is made of sclerenchymatous tissue. The cells of this tissue are dead. They are long and narrow as the walls are thickened due to lignin (a chemical substance which acts as cement andhardens them). Often these walls are so thick that there is no internal space inside the cell. This tissue is present in stems, around vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts. It provides strength to the plant parts.<br>

Sclerenchyma is the tissue which makes the plant hard and stiff. We have seen the husk of a coconut. It is made of sclerenchymatous tissue. The cells of this tissue are dead. They are long and narrow as the walls are thickened due to lignin. Often these walls are so thick that there is no internal space inside the cell. This tissue is present in stems, around vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts. It provides strength to the plant parts.<br>

The cell wall of sclerenchyma cells in plants like jute and hemp contain elongated, thread like thick walled cells called fibres.Since fibres are flexible and elastic they are used in coir industries to make gunny bags and ropes.<br>

The cell wall of sclerenchyma cells in plants like jute and hemp contain elongated, thread like thick walled cells called '''fibres'''.Since fibres are flexible and elastic they are used in coir industries to make gunny bags and ropes.<br>

 

http://www.transtutors.com/Uploadfile/CMS_Images/2871_Sclerenchymatous.JPG

http://www.transtutors.com/Uploadfile/CMS_Images/2871_Sclerenchymatous.JPG