Theories of ascent of SAP

Here are following theories which explain the ascent of sap in plants: a) Root pressure (b) Capillarity (c) Vital theory and (d) Cohesion-tension theory. (a) ROOT PRESSURE The hydrostatic pressure generated in the root which forces the water upward in the stem is called root pressure. Root pressure forces the water up from below. But it is believed that root ...

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Types Of Transpiration

Transpiration in Plants and its types The evaporation of water from the aerial part of plant is called transpiration. Transpiration is not a purely ph) sical process like evaporation. It is a vital phenomenon. It plays important role in the cell. –11e amount of water lost In transpiration is very large. It exceeds the final dry weight of the plant ...

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Environmental Factors That Affect The Rate Of Transpiration

Following factors affect the rate of transpiration: (a) External factors Humidity of air Water is evaporated through the stomata. This follows the simple law of diffusion. ‘Ibis diffusion can take place only if the water vapor content of the outer atmosphere is less than that of the inter-cellular spaces of the leaf. Transpiration is negligible in an atmosphere saturated with ...

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SEX DETERMINATION

SEX DETERMINATION The chromosomes which determine sex in the different organisms are called sex chromosomes. ‘Fhe term –sex– refers to the processes that enable species to exchange materials between homologous chromosomes. Ii causes recombination. Recombination is essential to their mechanism for reproduction. Work on inheritance of sex started after discovery of Menders ork in 1900. The discovery of sex chromosomes ...

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Bentham and Hooker Classification system

1 his system was proposed by George Bentham and Joseph Dalton Hooker. They proposed natural classilication system. .[heir system as published ill Genera Plantarum. They divide the seed plants into 202 orders. .[heir system was chiefly based on De Condone. Advantage of Bentham and Booker Classification system: . It is oased on natural classification system. It changed the artificial classification ...

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Carolus Linnaeus Classification system

The classification system of Linnaeus was based on floral characteristics. He chiefly used characters of stamen’s. Therefore, his system is called sexual system. This system is very convenient for the identification of plants. I le presented his classification system in two books. These books are Species Plantarum and Genera Plantarum. Advantages of Linnaeus system: Linnaeus was first to introduced some ...

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Epidermis

EPIDERMIS Epidermis forms the outermost layer of cells on the primary plant body. It is present over stem. roots, leaves, flowers and fruits. In most plant. epidermis is composed of single layer of cells. But two or several layers are also found in different plants. When it is composed of single layer, it is called hypodermis. When it is composed ...

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Xylem and Phloem

XYLEM Xylems are non-living conducting tissues. They conduct water and dissolved salts from root to different parts of plant. Xylem also forms \S ood in plants. It supports plant body. Xylem tissues are present  only in tracheophytes. Composition of XylemXylem is composed of thllow Mg types of tissues only in tracheophytes. Composition of Xylem Xylem is composed of thllow Mg ...

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Sclerenchyma Tissues

The lignified tisries .vhich lack protoplast at maturity are called sclerenchyma. Hey have thick secondary wall. These are main strengthening tissues of plant. Sclerenehyma cells are found in all parts of plant. They: are present in both ground tissues and vascular tissues. Sclerenchyma has two types: Fibers and sclereids (a) Fibers Very long and narrow sclerenchymatous cells with tapering ends ...

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PARENCHYMA AND COLLENCHYMA TISSUES

The group of cells performing some collective function is called tissue. Tissues organize the body of plant for performing different function. Many types of tissues associate with each other to form tissue system. Vascular system is an example of tissue system. The tissues have following characteristics: Tissues are composed of many cells. These cells may be of one type or ...

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