Question

Observe the experiment. This experiment was famous as:

A. Blender
B. Lazzaro’s experiment
C. Swan necked
D. Oparin’s origin of life

Answer 1

This experiment is famous for the type of flask used by Louis Pasteur. In 1859, Louis Pasteur developed this special apparatus and used in his experiment to prove that the fermentation takes place due to the particles in the air rather than the air itself.

Complete answer:
Louis Pasteur experiments to check whether sterile nutrient broth could spontaneously generate microbial life. To check this, Pasteur set up the two experiments. He added the nutrient broth in both the experiment flask. The flask is bent or S-shaped. Now the boiled or heated the flask with broth so that it kills the pre-existing microbes in it. After the broth gets sterilised, Pasteur broke the tube or swan neck of the flask of experiment 2 and exposed broth within them to air and the flask in experiment 1 was left alone. After some time, he observed that dust particles from the air fell into the flask of experiment 2. Whereas the flask of experiment 1, dust particles from the air remain at the tip of the tube or swan neck and keep the broth sterile. The broken flask was seen cloudy as a result of the microbial growth but the unbroken flask was seen clean. Thus, the experiment refuted the notion of spontaneous generation.
Lazzaro’s experiment: Lazzaro Spallanzani was an Italian scientist; he was the first one to disprove the spontaneous generation. In his experiment, he proved that microorganisms coming from the air can be killed by boiling.
Oparin’s origin of life: Two scientists named Oparin and Haldane proposed that the first life form come from the pre-existing non-living organic molecules. The formation of life is introduced by chemical constituents.

Hence, the correct answer is option (C).

Note: The gooseneck flask is another name of the swan neck flask. The flask with a particular shape of the tube leading into it formed the swan neck like structure. The significance of this flask is, it slows down the motion of air through the tube and particles present in the air like bacteria become trapped in moisture on its inner surface. Therefore the liquid in this type of the flask remains sterile as long as the sterile liquid does not contact the contaminated liquids in the tube.