Question

Fermentation to produce alcohol by yeast(saccharomycces) is due to

Answer 1

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Fermentation to produce alcohol by yeast is due to anaerobic respiration or anaerobic breakdown of sugar to produce ethanol and Co2 in it.

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Answer 2

Due to Anaerobic Respiration or Aerobic breakdown.

$\textsf{ \underline { \underline { \: \: \: Explanation\:!! \: \: \: } }}$

↪ Take 10 ml of 10 Per Cent glucose in solution in a test tube.

↪ Add to it a pinch of baker's yeast suspended in water or few ml. of yeast suspension used in a bakery.

↪ Cover the surface of the liquid with oil so as to prevent contact with air.

↪ Tightly close the tube with a rubber stopper.

↪ Introduce the short end of delivery tube through rubber stopper so as to reach the air inside the tube.

↪ Cover the rubber stopper with vaseline to make it air tight.

↪ The outer long end of the delivery tube is dipped into the lime water contained in a beaker.

↪ Place the test tube A in warm water (37°C - 38°C) in a beaker.

↪ You will observe that Lime water turns milky, indicating the evolution of carbon-dioxide from the yeast preperation.

↪The level of the lime water in the delivery tube does not rise, Showing that there is no decline in the volume of gas in test tube and thus no utilisation of Oxygen by Yeast.

↪ Let the preperation be stand for a day or so.

↪ When You open the rubber stopper of tube, there is a smell of alcohol indicating the formation of Ethanol.

Note :- From this Activity it can be inferred that yeasts respire anaerobically to ferment glucose to ethanol and carbon dioxide.