1. Life Comes From Life
Notes 2.1c

2. Life Comes From Life
Living things arise from living things through reproduction.
Today we know that flies come from flies.
But 400 years ago, people believed that life could appear from non-living material.
For example, people thought flies came from rotting meat.

3. Life Comes From Life
The mistaken idea that living things can arise from nonliving sources is called spontaneous generation.
It took hundreds of years of experiments to convince people that spontaneous generation does NOT OCCUR!

4. Redi’s Experiment Time: 1600s Scientist: Francesco Redi – Italian
Redi designed an experiment to show that flies do not arise from decaying meat.
Remember: A controlled experiment is when you carry out 2 experiments at the same time with only 1 difference between them.

5. Redi’s Experiment
In Redi’s experiment, the manipulated variable was whether or not to cover the jar.

6. Redi’s Experiment

7. Pasteur’s Experiment Time: Mid 1800s Scientist: Louis Pasteur – French
He demonstrated that new bacteria appeared in broth only when they were produced by existing bacteria.

10. Conclusions
The experiments of Redi and Pasteur helped to convince people that living things do not arise from nonliving material.