Sunday, August 1, 2010

THE LIVING CONDITION

THEORY OF SPONTANEOUS GENERATION



Spontaneous Generation (Abiogenesis)

- believed that living things may arise from nonliving substances.



Aristotle

- noted in his book Historia Animalium: mullet, a kind of fish, is the mud

of a dried-up pond that came to life spontaneously when rain filled the pond.



John Turberville Needham

- English biologist

- boiled mutton gravy, poured into a glass vial, and corked it. After a afew days,

the gravy was swarming with microorganisms.



F.A. Pouchet

- respected French scientist

- prepared hay infusion and introduced "artificial air". In a few days, the infusion

contained a rich variety of microorganisms.





THEORY OF BIOGENESIS



Biogenesis

- states that life comes only from life



Francesco Redi

- Italian physician

- proved that maggots were not spontaneously generated from rotting meat.



Lazzaro Spallanzani

- Italian biologist

- repeated Neddham's experiment but failed to obtain growth of organisms

by spontaneous generation

- he used vessels that are tightly closed.



Louis Pasteur

- one of the graetest biologist of all time from France.

- made an experiment which proved that air was a source of contamination.

- used flasks for his experiments.



Stanley Miller

- proved in his laboratory the possibility of forming amino acids and other organic

molecules from a mixture of hydrogen, methane , and ammonia.



Characteristics of Living Things
  • Living things have a specific organization
  • Living things undergo metabolic processes in their bodies
  • Living things can move
  • Living things can react to stimuli or changes in their surroundings
  • Living things are capable of growth
  • Living things can reproduce
  • Living things can adapt to their environment

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