Life and its Origin

Subject: Biology

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This note contains different theories of life in detail.They performed an experiment to conclude unicellular organism could not originate from nonliving things.
Life and its Origin

Life is the power that organisms possess to maintain their existence and reproduce themselves. Various scientists proposed different theories regarding the origin of life. Some popular theories are discussed below;

Special Creation Theory

According to this theory, all plants and animals existing on the earth today are created by the supernatural power of a god.

Spontaneous generation theory(Abiogenesis or autogenesis)

Ancient Chinese, Greek and Egyptian believed in spontaneous generation of life. According to this, "Life is originated from nonliving things or abiotic factors gradually or automatically." Eg; frog, fish, snail were formed by clay.

Biogenesis

According to this theory, "the new organism is originated from pre-existing ones."

Redi's experiment

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Francesco Redi(1684) demonstrated to show maggots could not be formed from the flesh of meat, but the smell of meat attracted the flies which lay eggs. When eggs hatch, maggots appeared on meat. For that, he has taken 8 jars in which he kept a piece of boiled meat in all of them. 4 jars are made sealed whereas remainings are opened. He found the maggots in opened jars rather than sealed jars.

Lazzaro and spanllanzenil(1969)

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They performed an experiment to conclude unicellular organism could not originate from nonliving things. For that 8 bottles are taken with heg influsion. 4 of them are corked and remaining are made air-tight. After few days, they found microorganisms in corked bottles not in air-tight bottles.

Louis experiment

Louis parleus(1862) disproved the concept given by abiogenesis and performed the experiment with swan neck flask supporting biogenesis.

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Experiment;

  • Pour the nutrient solution in swan neck flask.
  • Bend the neck of the flask into S-shaped on heating.
  • Boil the solution to kill and derive out bacteria.
  • Cool, the solution and the dust particles trap in bending part solution becomes solute.
  • Break the bending part. Dust particles come in contact with the solution. After few days, bacterial colony appears on the solution.

Cosmozoic theory

Ritcher(1864) believed that life on earth originated from spores came from other planets called panspermia.

Things to remember
  • Life is the power that organisms possess to maintain their existence and reproduce themselves. 
  • Francesco Redi(1684) demonstrated to show maggots could not be formed from the flesh of meat, but the smell of meat attracted the flies which lay eggs.
  • Louis parleus(1862) disproved the concept given by abiogenesis and performed the experiment with swan neck flask supporting biogenesis.
  • They performed an experiment to conclude unicellular organism could not originate from nonliving things. 

 

  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.

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