05 Origin and Evolution of life - part 01- Origin of life

05 Origin and Evolution of life - part 01- Origin of life


Origin of life  (Protobiogenesis) :
  • The living matter shows attributes or characters like - 
  1. responsiveness
  2. growth
  3. metabolism
  4. energy transformations and 
  5. reproduction.
  • As far as origin of life is considered, it has remained an enigma for intellectuals at all times. 
  • Despite of advancements in various fields like biochemistry, astrobioloy, geography, molecular biology, etc. scientists are unable to ascertain the truth. 
  • Various theories and hypotheses have been proposed to find the probable answer to this question.
 a. Theory of special creation : 
  • It is the oldest theory and is based on religious belief without any scientific proof. 
  • It states that all living organisms are created by a super-natural power. 
b. Cosmozoic theory/Theory of Panspermia: 
  • This theory advocates that life did not arise on the planet Earth. 
  • It may have descended to the earth from other planets in the form of spores or micro-organisms, called cosmozoa/ panspermia. 
  • Recently, NASA has reported fossils of bacteria-like organisms on a piece of Martian rock recovered from Antarctica. 
c. Theory of spontaneous generation (Abiogenesis) : 

  • According to this theory, life originated from non-living materialspontaneously. 
  • This theory was disproved byLouis Pasteur.
Theory of biogenesis : 
  • According to this theory, living organisms are always produced from pre-existing living forms, by process called reproduction. 
  • Theory of biogenesis however could not explain origin of first life on earth but could explain only the continuity of life. 

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