Question

Which of the following theories was disapproved by the swan neck experiment of Louis Pasteur?
A) Abiogenesis
B) Biogenesis
C) Spontaneous generation theory
D) None of the above

Answer 1

Hint: A swan neck flask also known as gooseneck flask. It is a type of flask that has a tube coming to it with a particular shape. This “swan neck” shape helps to slow down the movement of air and prevent bacterial entry through the tube.

Complete answer :
Louis Pasteur was a French chemist and biologist. He was doing research related to germs to understand the cause of diseases. Once he conducted an experiment using an S-shaped flask known as “swan neck flask”. He added broth enriched with nutrients in one of the bottles and boiled. The process of boiling to kill any germs present is known as pasteurisation. He left the infusion undisturbed for some time. After the prescribed time he found that the broth colour was not changed. Since the flask had S-shaped neck bend, the germs were not able to enter the same, thus preventing contamination of the liquid.
Louis repeated the experiment again by tipping the particles into the flask body. This time he observed that the germs entered the infusion and spoiled it completely. Hence he concluded that certain germs in the air spoil the broth. Thus he proved that the theory of “spontaneous generation” is wrong, which stated that living organisms can develop from non-living matter too. It was told that spontaneous generation was hypothetical.
Abiogenesis stated that life can arise from a non-living life matter.
Biogenesis is defined as creating a new living thing through reproduction.

So the correct answer is C Spontaneous generation theory.

Note:Spontaneous generation theory was created by Aristotle. Aristotle proposed that life can arise from a nonliving substance if the substance contained vital heat. This theory was persisting in the 17th century. Many scientists and researchers were working both to support and also to disprove this theory.