Origin of Life ppt notes

Name _________________________________
Origin of Life PPT Notes
Date ____________
Period _________
Aristotle & Spontaneous Generation
Spontaneous Generation = Theory proposed by ________________; Idea that living things can arise from
_____________ _____________; lasted almost _______ years; also called ____________________
People arrived at their beliefs by what they ___________; did NOT use the _____________ ____________;
conclusions were based on _____________________ _________________________.
Give 1 example of Spontaneous Generation.
Francesco Redi’s Experiment (1668)
Used open & closed flasks which contained _________________; Hypothesis = rotten meat does
Redi found that if a flask was closed _______ a lid so adult flies could not get in, ______________________
on the rotting meat within. In a flask ____________ a lid, maggots soon were seen in the meat because
________________________________ and more adult flies soon appeared.
Redi’s Evidence against spontaneous generation:
a. _________________ – maggots on meat
b. ______________ – no maggots on meat
c. ______________ – few maggots on gauze, none on meat
The results of this experiment disproved the idea of spontaneous generation for ______________ organisms,
but people still thought _________________ organisms like algae or bacteria could arise that way.
Did Redi use the Scientific Method?
Disproving Spontaneous Generation of Microbes
Anton van Leeuwenhoek (1674)—made a simple ___________________; examined water and visualized
tiny animals, fungi, algae, and single celled protozoa; he called these organisms “_______________”; by the
end of the 19th Century, they were called _______________________.
10. John Needham (1745)—experiments showed that __________________ flourished in various soups that had
been exposed to the ___________; seemed to support ___________________ __________________
11. Needham’s Error: bacteria were ________________ _______________ in Needham’s soups; he didn’t
___________ long enough to ____________ the microbes.
12. Lazzaro Spallanzani’s (1765)--_______________ soups for almost an hour and _____________ containers
by melting the slender necks closed; soups remained _____________; after he broke the seals, the soups
became __________________________________.
13. Spallanzani’s Critics said sealed vials did not allow enough ___________ for organisms to survive and that
prolonged heating destroyed “_____________________”
The Theory Finally Changes
14. Louis Pasteur (1864)---finally __________________ spontaneous generation; used _____________ flask
kept ______________ out but let __________ in; proved microbes only come from _____________
15. Biogenesis = _________________ from ______________
Name _________________________________
Origin of Life PPT Notes
Date ____________
Period _________
Francesco Redi: Francesco Redi was an Italian physician and scientist born in 1626. He was also a prolific
author, writing both creatively and scientifically. He produced the groundbreaking book "Experiments on the
Origins of Insects" in 1668.
Redi's Theory: During Redi's time a common theory was abiogenesis, which asserted that living organisms can
spontaneously grow from dead or inorganic matter. Francesco's work to disprove abiogenesis would later play a
crucial role in the development of cell theory.
Experiment: The supporting argument for abiogenesis at the time stemmed from the appearance of maggots on
rotting meat; it was thought that the meat was turning into maggots. Redi performed a series of experiments with
meat, leaving some meat covered and some uncovered. He discovered that maggots only appeared on the
uncovered meat. He also spent time studying the maggots and realized that they eventually turned into flies. His
research didn't garner much respect at the time, but it did serve to cast doubt on the spontaneous generation theory.
Read more: Francesco Redi's Cell Theory | eHow.com http://www.ehow.com/facts_7420090_francesco-redi_s-cell-theory.html#ixzz23CSPCqUp
Spontaneous Generation: For most of the history of spontaneous generation, notable inquirers were not
focused so much on the origin of life (to many that was left up to a deity) as the issue of life springing at random,
fully formed from nonliving matter. Francesco Redi cast aspersions upon the idea as early as the 17th century, but
it took until French chemist Louis Pasteur in 1859 to sound the death knell. Pasteur boiled meat in a flask (since it
was believed that life arose from rotting meat), heated the neck to make it pliable, and bent the neck in an S shape.
The idea was that air could get out but microorganisms could not get in; they'd settle in the neck of the flask. He
found that no organisms were spontaneously created. Instead, they entered only when Pasteur straightened the
neck and allowed them in.
Read more: The Theories of Spontaneous
Generation and Biogenesis | eHow.com