Explain Kuhne's experiment and the action of enzyme zymase.

Explanation

Demonstration of alcoholic fermentation :
1. Take a kuhne's fermentation tube which consists of an upright glass tube with side bulb.
2. Pour 10% sugar solution mixed with baker's yeast into the fermentation tube so that it is filled and plug the mouth with cotton.
3. After some time , the glucose solution will be fermented .
4. The solution will give out an alcoholic smell and level of solution in glass column will fall due to the accumulation of `CO_2` gas.

5. It is due to presence of zymase enzyme in yeast which converts the glucose solution into alcohol and `CO_2` . Now introduce a pellet of KOH into th tube , the KOH will absorb `CO_2` and the level of solution will rise in upright tube.