Answer
Significant role of water is listed below.
1. Polar nature (universal solvent)
Water acts as universal solvent and can dissolve a variety of inorganic and organic molecules. Due to hydrogen bond water molecule is polar and make them able to interact with each other. the charged region on each molecule are attracted to oppositely charged region on neighbouring molecules, forming weak bonds. Since the positive charged region int his type of bond is always hydrogen atom, the bond is called hydrogen bond. this bond is often represented by a dotted line because a hydrogen bond is easily broken. Because of hydrogen bonding, water is a liquid at room temperatures suitable for life, it boils at 100 degree centigrade and freezes at 0 centigrade.
2. Water Absorb high heat with little change
The amount of heat required to raise the temperature of 1 gm water by 1 dgree is known as specific heat. water molecules have high specific heat. This means that a large increase in heat energy results in a relatively small rise in temperature. This is because much of the energy is used in breaking the hydrogen bonds, which restrict the movement of molecules. The many hydrogen bonds that link water molecules help water absorb heat without a great change in temperature. When water cools down heat is released. Water holds heat and its temperature falls more slowly than other liquids. This property of water in important not only for aquatic organisms, but also for all living organisms. Water protects organisms from rapid temperature changes and helps them to maintain their normal internal temperatue.
3. Water evaporate at high temperatue
The amount of heat required to convert water from liquid in to vapours is known as heat of vapourization. Water has high heat of vapourization, which means that water has high boiling point. Because water boils at 100 degree centigrade. it is in a liquid state at a temperature suitable for living things. This property of water helps to moderate the earth's temperature. It also gives animals, in a hot environment an efficient way to release excess body heat. When an animal sweats, body heat is used to vaporize the sweat thus cooling the animal. The high heat of vapourization means that a large amount of heat cab be lost with minimal loss of water from the body.
