Question

Some sugar solution is taken in a test-tube and a little of substance X in powder form is added to it. The mouth of test-tube is closed with a cork and allowed to stand for sometime. On opening the cork, a characteristic smell of substance Y is obtained and a gas Z is also observed to be formed. The gas Z extinguishes a burning matchstick.

1. What could be (i) X, (ii) Y, and (iii) Z?
2. What is the process of converting sugar into substance Y by the action of X known as?
3. What type of respiration is exhibited by X in the above process?

Answer 1

1. 1. X is yeast.
   2. Y is ethanol.
   3. Z is carbon dioxide.
2.  The process of converting sugar into ethanol (Y) by yeast (X) is known as fermentation (or alcoholic fermentation).
3. The type of respiration exhibited by yeast in this experiment is anaerobic respiration, meaning it breaks down sugar molecules completely without using oxygen.