Class 12 | Biology | Evolution | Origin of LifeClass 12 | Biology | Evolution | Origin of Life
In this module, you will learn about the origin of life.
Looking at the pictures of these extinct prehistoric animals, it is difficult to believe that they had once walked on our planet.
In fact, the earth and its numerous life forms were originally different. To understand the changes in life forms on earth over millions of years, we need to know how life originated.
The origin of life forms or biodiversity is interlinked with the evolution of the earth, which is again closely associated with the evolution of the universe.
The universe is vast, comprises many galaxies and is almost twenty billion years old.
The Big Bang Theory attempts to explain the origin of the universe. According to this theory, a singular huge explosion caused the infinitesimally small, hot and dense universe to expand, which resulted in the lowering of temperatures. It even states that the universe continues to expand even today.
After the passage of time, gases such as hydrogen and helium got formed. They condensed due to gravitation and gave rise to different galaxies in the universe.
One of the galaxies known to us is the Milky Way, which contains the solar system and the earth is one of the planets in this system.
At the time of its formation, there was no atmosphere on the earth. Its surface was covered by water vapor, methane, carbon dioxide and ammonia released from the molten mass.
Gradually, the ultraviolet rays of the sun broke up the water, which was in the vapor state, into hydrogen and oxygen.
Hydrogen is a lighter gas than oxygen, escaped.
Thereafter, oxygen combined with ammonia and methane, which led to the formation of water, carbon dioxide, and other gases.
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