The enzyme complex from yeast that converts sugars such as glucose and fructose into ethyl alcohol and carbon dioxide during fermentation is called:

Introduction / Context:
Fermentation is a key biochemical process used in brewing, wine making and baking. During alcoholic fermentation, microorganisms such as yeast convert sugars like glucose and fructose into ethyl alcohol and carbon dioxide. This transformation is driven by enzymes, which act as biological catalysts. The question asks you to identify the specific enzyme complex from yeast that is directly responsible for converting sugars into alcohol and carbon dioxide, distinguishing it from other enzymes that act on carbohydrates.

Given Data / Assumptions:

• The substrate sugars include glucose and fructose.
• The products of the reaction are ethyl alcohol (ethanol) and carbon dioxide gas.
• The enzymes listed in the options include diastase, maltase, invertase, zymase and an unrelated digestive enzyme.
• We assume basic knowledge of carbohydrate digestion and fermentation.

Concept / Approach:
Different carbohydrate related enzymes perform different roles. Diastase breaks down starch into simpler sugars, maltase converts maltose into glucose and invertase splits sucrose into glucose and fructose. These enzymes prepare or modify sugars, but they do not themselves convert sugar into alcohol. The enzyme complex that actually catalyses the series of reactions in alcoholic fermentation is zymase, which is found in yeast cells. The approach is to recall which enzyme name is traditionally associated with alcoholic fermentation, as opposed to earlier stages of sugar breakdown.

Step-by-Step Solution:
Step 1: Recognise that the reaction described is the conversion of glucose and fructose to ethanol and carbon dioxide, the core of alcoholic fermentation. Step 2: Recall that diastase acts on starch, breaking it into maltose and other smaller sugars, but does not directly produce alcohol. Step 3: Maltase acts on maltose to release glucose molecules and is important in digestion, not directly in alcohol production. Step 4: Invertase hydrolyses sucrose into glucose and fructose, preparing fermentable sugars but again not converting them to alcohol. Step 5: Zymase is the enzyme complex present in yeast that catalyses the conversion of glucose and fructose into ethanol and carbon dioxide in the fermentation pathway. Step 6: Therefore, the correct answer is zymase, which directly carries out alcoholic fermentation.

Verification / Alternative check:
Historical experiments by biochemists showed that cell free extracts from yeast could ferment sugar to alcohol, and the active component responsible was named zymase. Today we know that zymase is not a single protein but a group of enzymes working together in glycolysis and subsequent steps leading to ethanol formation. Brewing and winemaking textbooks consistently refer to zymase as the yeast enzyme complex that drives alcoholic fermentation. In contrast, diastase, maltase and invertase are usually mentioned when discussing starch digestion and sugar processing, not the final conversion to alcohol. This confirms zymase as the correct choice.

Why Other Options Are Wrong:
Option A, diastase, is important in converting starch to maltose but does not produce ethanol. Option B, maltase, converts maltose to glucose, supplying more fermentable sugar, but it is not the enzyme that creates alcohol. Option C, invertase, prepares glucose and fructose from sucrose, again serving as a preliminary step. Option E, pepsin, is a protein digestive enzyme in the stomach and has nothing to do with carbohydrate fermentation. Only option D correctly identifies zymase as the enzyme complex from yeast that converts sugars into ethyl alcohol and carbon dioxide during fermentation.

Common Pitfalls:
Students sometimes confuse enzymes that prepare sugars with those that actually carry out fermentation. Because diastase, maltase and invertase all act on carbohydrates, it is easy to mix up their specific roles. Another pitfall is to think in very general terms and choose any familiar enzyme name rather than focusing on the final step that produces ethanol. To avoid confusion, remember that zymase is historically linked to alcoholic fermentation in yeast, while the other enzymes mainly break down complex carbohydrates into simpler sugars.

Final Answer:
The enzyme complex that converts glucose and fructose into ethyl alcohol and carbon dioxide during fermentation is Zymase, which catalyses the conversion of sugars to alcohol and carbon dioxide.