In industrial and biochemical processes, the conversion of sugar into alcohol by the action of microorganisms is called what?

Introduction / Context:
This question is about a key biochemical and industrial process: the conversion of sugars into alcohol and carbon dioxide. This process is widely used in brewing, wine making, baking, and certain industrial applications. The correct term for this sugar to alcohol conversion carried out by yeast or other microorganisms is fermentation. Recognising this term helps link everyday products like bread, beer, and wine to the underlying biochemistry.

Given Data / Assumptions:
- The process described is the conversion of sugar to alcohol.
- The options include moulding, infection, fermentation, and alcohol fixation.
- We assume common yeast based fermentation as in brewing and baking.

Concept / Approach:
Fermentation is a metabolic process in which microorganisms such as yeast convert sugars into alcohol and carbon dioxide in the absence of oxygen, or under low oxygen conditions. In alcoholic fermentation, glucose and other simple sugars are transformed primarily into ethanol and carbon dioxide. Moulding refers to the growth of mould fungi on surfaces, infection refers to harmful invasion by pathogens, and alcohol fixation is not a standard term for sugar conversion. Therefore, the correct technical term for sugar being converted into alcohol by microorganisms is fermentation.

Step-by-Step Solution:
Step 1: Identify the key transformation described: sugars such as glucose are being converted into alcohol.
Step 2: Recall that yeast, such as Saccharomyces species, carry out alcoholic fermentation, in which they use sugar as a substrate to produce ethanol and carbon dioxide.
Step 3: The process is widely used in producing beverages such as beer and wine and in baking, where carbon dioxide gas helps dough rise.
Step 4: The scientific name for this metabolic pathway is fermentation. Specifically, the type is alcoholic fermentation.
Step 5: Other options like moulding and infection describe different biological phenomena and not the sugar to alcohol conversion.
Step 6: Alcohol fixation is not a recognised standard term in this context, so it cannot be correct.

Verification / Alternative check:
Biology and chemistry textbooks describe fermentation as an anaerobic breakdown of carbohydrates, where yeast convert glucose to ethanol and CO2. The general equation for alcoholic fermentation can be written as glucose gives ethanol plus carbon dioxide plus energy. In everyday language, when grapes are fermented, their sugars are turned into wine. The same term is used for brewing beer from malted grains. No other term in the options is used in these contexts, confirming fermentation as the correct choice.

Why Other Options Are Wrong:
- Moulding: This refers to the growth of mould fungi on food or surfaces, often causing spoilage, but it does not necessarily describe sugar to alcohol conversion.

Why Other Options Are Wrong (continued):
- Infection: This refers to invasion and multiplication of harmful microorganisms in a host organism, which is a medical concept rather than a sugar conversion process.
- Alcohol fixation: This is not a standard term in biochemistry for any common process and is not used for the conversion of sugar to alcohol.

Common Pitfalls:
Learners may confuse different microbial processes, such as mould growth or infection, with fermentation. Some might think any microbial activity on food counts as fermentation, but fermentation specifically describes metabolic pathways that break down carbohydrates, often without oxygen, producing alcohol or organic acids. Associating fermentation with familiar products such as bread, beer, wine, yogurt, and pickles can help distinguish it from unrelated biological terms.

Final Answer:
Fermentation is the name of the process in which sugar is converted into alcohol by microorganisms.