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The diagram below shows a set up that was used to demonstrate fermentation.

Glucose solution was boiled and oil added on top of it. The glucose solution was
then allowed to cool before yeast suspension was added.
(a) Why was the glucose solution boiled before adding the yeast?
(b) What was the important of cooling the glucose solution before adding the yeast?
(c) What was the use of oil in the experiment?
(d) What observation would be made in test tube B at the end of the experiment?
(e) Suggest a control for this experiment.

Answer Text:
a)- To drive out or expel oxygen.
b)- To avoid killing yeast cells or denaturing enzymes in yeast.
c)- To prevent air (especially oxygen) from getting into the glucose and yeast suspension
d)- Lime water forms a white precipitate, bubbles are formed.
e)- Used boil yeast on glucose.