In the solar system of the milky way galaxy, earth was supposed to have been formed about 4.5 billion years back. ... However, this did not answer how the first life form came on earth. ... and that formation of life was preceded by chemical evolution, i.e., formation of diverse organic molecules from inorganic constituents.
|Title||:||NCERT CLASS 12TH(XII) BIOLOGY|
|Author||:||NCERT, DIGITAL DESIGN|
|Publisher||:||Digital Designs -|