The importance of water for life.
Water has many roles in living organisms and life on earth is impossible without it. It makes up between 60% and 95% of the fresh mass of the organisms. In a water molecule, two hydrogen atoms are joined to an oxygen atom by covalent bonds. This makes it a stable molecule. The oxygen nucleus attracts the electrons more than the hydrogen nuclei do. This results in the oxygen atom having a ¥ä- charge and the hydrogen atoms having a ¥ä+ charge. This water molecule is referred to as dipolar due to the uneven charge distribution.
Water plays a very important role in animals. It maintains the process of homeostasis to maintain the relatively constant temperatures within the body. Water has a high specific heat capacity, indicating that it requires a lot of energy to raise the temperature of 1Kg by 1¢ªC. Also, a lot of heat energy must be lost for the temperature of the same mass of water to fall by 1¢ªC. This is important because it means that sudden changes in the temperature, which may upset metabolic reactions in cells, are avoided. These chemical reactions are allowed to tale place within a narrow temperature range so that rates of reaction are more constant. However, for organisms th
If the water stress is sufficiently severe the plant may release a growth inhibitor, which triggers stomatal closure. Transpiration maintains a water potential gradient by which water moves from the soil into the root hairs, and across the cortex of the root to the central vascular tissue. This is due to water having a maximum density of 4 C. Nutrient ions are absorbed from the floodwater. Humidity is important for its effect on the rate of water loss by plants and animals. Water flows readily through narrow capillaries due to the fact that water molecules can slide over each other as they have very low viscosity. At the gill surfaces the fish loses water by osmosis and also gains ions from the seawater by diffusion, thus increasing the concentration of the body fluids. Without water there will be a shortage of oxygen. Simultaneous movements of water uptake and water loss by transpiration show that the supply of water into the plants often falls behind the rate of water loss at times of peak transpiration. Many of the plants have adapted to containing water storage cells. Water contains the isotope oxygen-16. Animals of arid regions are adapted to survive with little water.