Miller - Urey experimentally proved Chemical Origin of Life that was said by Oparin- Haldane. They simumulated early earth conditions in their experrimental set up and they allowed to run. As a result they observed formation of simple organic molecules from inorganic molecules.

R. H. Whittaker classified all the organisms into 5 kingdoms based on cell type, cell complexity of organisms, mode of nutrition, Habitate and evolutionary relationships between organisms. The 5 kingdoms are 1. Monera 2. Protista 3. Fungi 4. Plantae 5. Animalia.