5 Relations.pdf

‫بسم هللا الرحمن الرحيم‬  Physiological Importance of Water The only way in which an environmental factor such as water can affect plant growth. In summary, decreasing water content is accompanied by loss of turgid ‫التمدد‬and wilting‫ والذبول‬, cessation of cell enlargement, closur...

‫بسم هللا الرحمن الرحيم‬  Physiological Importance of Water The only way in which an environmental factor such as water can affect plant growth. In summary, decreasing water content is accompanied by loss of turgid ‫التمدد‬and wilting‫ والذبول‬, cessation of cell enlargement, closure of stomata, reduction in photosynthesis, and interference with many other basic metabolic processes. Eventually, continued dehydration causes disorganization of the protoplasm and death of most organisms. An aqueous solution is water that contains dissolved substances In a solution, the dissolving media is the solvent In a solution, the dissolver particles are the solute A solute is the dissolved substance in a solute A solvent is the major component in the solute The solvent is often water Function Of Water In Plant The importance of water can be summarized by listing its most important functions under four general headings.  Constituent: Water is as important a part of the protoplasm as the protein and lipid molecules which constitute the protoplasmic framework, and the reduction of water content below some critical level is accompanied by changes in structure and ultimately in death. Function Of Water In Plant  Solvent: A second essential function of water in plants is as the solvent in which gases, minerals, and other solutes enter plant cells and move from cell to cell and organ to organ.  The relatively high permeability ‫النفاذية العالية نسبيًا‬ of most cell walls and protoplasmic membranes to water results in a continuous liquid phase, extending through out the plant, in which translocation of solutes occurs. Function Of Water In Plant  Reactant:  Water is a reactant or substrate in many important processes, including photosynthesis and hydrolyte processes such as the amylase- mediated hydrolysis of starch to sugar in germinating seeds. Function Of Water In Plant  Maintenance of Turgidity‫الحفاظ على الصالبة‬:  Another role of water is in the maintenance of the turgor which is essential for cell enlargement‫ لتضخم الخاليا‬and growth and for maintaining the form of herbaceous plants.  Turgor is also important in the opening of stomata and the movements of leaves, flower petals, and various specialized plant structures.  Inadequate water to maintain turgor results in an immediate reduction of vegetative growth. Circular Exam