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water vapour, etc.
5. Miller’s experiment provided experimental evidence for chemical evolution.
(i) The experiment was carried out by SL Miller and HC Urey in 1953.

(ii) He took a closed flask containing CH 4,H 2,NH 3 and water vapour at 800°C and

created electric discharge. These conditions were similar to those in primitive
atmosphere.
(iii) After a week, formation of amino acids were observed. Complex molecules like
sugars, nitrogen bases, pigments and fats were seen in the flask by other scientist.
(iv) Analysis of the meteorite also revealed the presence of similar compounds.
(v) Chemical evolution of life was more or less accepted.

6. Origin of First Cell
(i) First non-cellular life forms originated three million years ago.
(ii) These molecules were like RNA, protein and polysaccharides.
(iii) Cellular life form first evolved about 2000 million years ago.
(iv) These were single-celled formed in aquatic environment.

(v) This form of abiogenesis, i.e. the first form of life arose slowly through
evolutionary
forces from non-living molecules It is accepted by many scientists.
7. Evidences of evolution come from
(i) Palaeontology (ii) Comparative anatomy and morphology
(iii) Biochemical/Physiology (iv) Biogeography