Question

Pasteur succeeded in disapproving the spontaneous generation theory, because

• A. Of the fact that sample of yeast taken by him was dead
• B. Of the clear surroundings of his laboratory
• C. He was ingenious in drawing out the neck of glass flasks, so as to provide access of air but not to micro-organisms
• D. He was very lucky

Answer 1

Answer: (C)

He was ingenious in drawing out the neck of glass flasks, so as to provide access of air but not to micro-organisms

Louis Pasteur designed an experiment to test whether sterile nutrient broth could spontaneously generate microbial life. To do this, he set up two experiments. In both, Pasteur added nutrient broth to flasks, bent the necks of the flasks into S shapes and then boiled the broth to kill any existing microbes. After the broth had been sterilized, Pasteur broke off the swan necks from the flasks in experiment 1, exposing the nutrient broth within them to air from above. The flasks in experiment 2 were left alone.

Over time, dust particles from the air fell into the broken flasks of experiment 1. In experiment 2, dust particles remained near the tip of the swan necks, but could not travel against gravity into the flasks, keeping the nutrient broth sterile. The broth in the broken flasks quickly became cloudy, a sign that it teemed with microbial life.

However, the broth in the unbroken flasks remained clear. Without the introduction of dust on which microbes can travel, no life arose. Thus, the Louis Pasteur experiment refuted the notion of spontaneous generation.

So, Pasteur succeeded in disapproving the spontaneous generation theory, because he was ingenious in drawing out the neck of glass flasks so as to provide access of air but not to micro-organisms.

Therefore, the correct answer is 'He was ingenious in drawing out the neck of glass flasks, so as to provide access of air but not to micro-organisms'.