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 some time. 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.

(a) What could be (i) X, (ii) Y, and (iii) Z ?


(b) What is the process of converting sugar into substance Y by the action of X known as? (c) What type of respiration is exhibited by X in the above process ?

(a) (i) Yeast (ii) Ethanol (iii) Carbon dioxide

(b) Fermentation is the process by which sugar converts into ethanol by the action of Yeast.


(c) Fermentation is an example of anaerobic respiration which is done by yeast (X) in the above experiment.


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