Hydrogen bond is weak attractive force between slightly positive hydrogen atom of one molecule and slightly negative atom in another or the same molecule. Many hydrogen bonds taken together are relatively strong. Hydrogen bonds between complex molecules of cells help maintain structure and function. Because water is a polar molecule, water molecules are hydrogen bonded to each other. The temperature of liquid water rises and falls more slowly than that of most other liquids.
Water has a high heat of vaporization.
Hydrogen bonds between water molecules require a large amount of heat to break. When animals sweat, evaporation of the sweat takes away body heat, thus cooling the animal. Water is universal solvent, facilitates chemical reactions both outside of and within living systems. Water is a universal solvent because it dissolves a great number of solutes. Ionized or polar molecules attracted to water are hydrophilic.