The defining characteristic of a water cycle is that it has the same starting and ending point. The water cycle is also known as the hydrologic cycle. It shows the cyclic path through which water moves in nature.
The water cycle is a part of the biogeochemical cycle.
The biogeochemical cycle shows how certain elements and compounds moves between living organisms and the earth.
All living organisms are essentially dependent of water and it is exchanged with the environment around.
Some key components of the water cycle are precipitation, ocean, living organisms, ground water, infiltration, surface run off, evaporation etc.
Reproduction, Heredity, Variety in fitness of population, and variety in characters among the population are all four conditions for natural selection.
