(3) Zymase Explanation: ‘ The fermentation of sugar into ethanol is one of the earliest biotechnologies employed by humanity. Fermentation of fermentable sugars by suitable yeast produces ethanol (ethyl alcohol). Yeast is a single celled fungus containing a number of enzymes useful during fermentation. Brewers yeast and **** yeast, for example, contain zymase, an enzyme that can convert glucose to ethanol.