Chapter 1 section 3 (where does life come from) 2011
Chapter 1: Nature of Science Section 3: Where Does Life Come From?
A. Spontaneous Generation 1. Theory that living things could come from non- living things. a. Rain creates worms; meat grows maggots. 2. This theory was accepted for hundreds of years. a. Scientists did not believe this and had to prove it wrong.
3. 1668 Francesco Redi tested the maggots and meat belief. a. Took 2 identical raw pieces of meat and put them into 2 identical jars. b. Covered one of them with a piece of light cloth. (so air could get through) c. Waited. d. Upon his return he found that the uncovered jar had maggots on the meat, but the covered jar did not. e. Since both jars did not have maggots, he stated that SG (Spontaneous Generation) had to be wrong. f. His experiment did not disprove SG entirely.
B. Louis Pasteur and Biogenesis. 1. Louis Pasteur was a French chemist that tested broth. (meat juices) a. Boiled broth to make it sterile. b. Placed into an s-shaped flask. (these flasks allows air to enter the broth but not dust; all the dust gets caught in the curve of the S. c. Upon return he found no contamination to any of the flasks. d. He then tilted the flask so the dust could enter the broth, within days it was contaminated. e. Concluded that broth does not make germs, but is contaminated by the dust in the air.
2. Pasteur’s experiment led to the theory of BIOGENSIS. a. Living things come only from other living things. b. See page 20 in your textbook!!!!
C. Life’s Origin 1. Earth is believe to be 4.6 billion years old. 2. The oldest found life is about 3.5 billion years old. 3. 1924 Alex Oparin: Russian scientist suggested Earth’s atmosphere had no oxygen in it but had ammonia, hydrogen, methane, and water vapor. a. Believed these gases combined to form the simplest form of life (bacteria) and then the evolution cycle began. b. This is only one belief of how life was created!!!!
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.