Answer:
Designing a controlled experiment that exposed the boiled broth to air with an S shaped curve
Step-by-step explanation:
The supporters of spontaneous generation theory stated that the life did not come from outer space but life comes spontaneously from non-living matter present on earth. Louis Pasteur disproved this theory by a careful experiment and proved that life can come only from pre-existing life forms. In his experiment he tried to show that life forms originated in the boiled broth which was open to air, since air contain pre-existing life forms. Pasteur took two flasks and sterilized them to make sure they are free from microbes. He made a thick soup of yeast and water called the broth in both the flasks. The broth was heated to make sure that the virus is killed. One flask was left open to air and the second flask had a S shaped curved neck. The second flask was not in direct contact with air. He showed that only in the first flask which was open to air, new microbes appeared but not in the second flask. So the new life forms didn't come from dead yeast but from the air which carry pre-existing microbes.
Hence it was proved that life cannot come from non-living objects and could only arise from living organisms.