Page 1 :
well-adapted to the due to their characteristicsa, Natural a of a, 200, favoured by nature to survive., of plants and animals which are advantageous to mankind., understanding of the, Origin of life can be understood better only by an, Origin of the Universe and that of the Earth., Origin of the Universe, Universe is about 20 billion years old., It inclues clusters (groups) of galaxies, which contain clouds of gas and, dust., The Big Bang Theory of the origin of the universe explains that the universe, arose from a huge explosion that cannot be imagined in physical terms., As a result, the universe expanded, temperature decreased; hydrogen and, helium were formed sometime later., The gases condensed under gravitation and formed the galaxies of the, present day universe., Origin of the Earth, Earth was formed about 4.5 billion years ago, in the solar system of ue, milky-way galaxy., the molten mass., The UV rays from the sun broke up water into hydrogen and oxygen, The lighter hydrogen gas escaped from the surface, while, with other compounds (like methane, ammonia etc) to form water,, dioxide and other gases., oxygen, combined, carbon, From the oxygen. the oZone layer was also formed.