INTRODUCTION

     All biochemical reactions in plants and other organismstake place in aqueous solutions. Water is required for transportation of organic substances and minerals between cells. In plants specialized tissues formed by phloem and xylem cells constitute the so called vasculature used as the transport route between different parts of the plant. Herbaceous plants need water to create turgor pressure, which in turn is needed to keep stems and leaves upright. Evaporation of water, i.e. conversion of water to a gaseous form (steam), requires energy and is used to control temperature in plant tissues. The essential functions of water in plants are dealt with in water relations in plants.
    Plants are essential for life on Earth since they are largely responsible for converting solar energy into a biochemical (organic) form. This reaction is called Photosynthesis. It takes place on membrane structures (Thylakoids) in cellular organelles called Chloroplast. It involves one molecule of CO₂ and two molecules of H₂O, which reacts the help of solar energy to form one molecule each of a carbohydrate(CH₂O), water and oxygen.