Question

The formation of alcohol by yeast is
(a) Anaerobic process
(b) Extracellular
(c) Microbial
(d) All of the above

Answer 1

Hint: It's a biochemical process during which yeasts convert sugars to ethanol, ${ CO }_{ 2 }$, and other metabolic byproducts that contribute to the chemical composition and sensorial properties of the fermented foodstuffs. This process has occurred without oxygen.

Complete answer:
Sugars are the last word source for yeast. It converts the sugar into pyruvate by the method of glycolysis. Under anaerobic conditions, the pyruvate is reduced to acetaldehyde and eventually to ethanol and ${ CO }_{ 2 }$ as waste products. It's an extracellular process that produces two ATP.

Additional Information: The use of alcohol fermentation is often traced back to history for thousands of years. The chemical reactions of alcoholic fermentation are the subsequent $Pyruvic\quad acid\rightarrow { CO }_{ 2 }+acetaldehyde+NADH\rightarrow ethanol+{ NAD }^{ + }$ In the first reaction, it is catalyzed by pyruvate decarboxylase, a cytoplasmic enzyme, with a coenzyme of cocarboxylase (TPP, which is derived from vitamin B1 and also called thiamine). A carboxyl is faraway from acid, releasing ${ CO }_{ 2 }$ as a gas. The loss of ${ CO }_{ 2 }$ reduces the dimensions of the molecule by one carbon, making acetaldehyde. In the second reaction, it is catalyzed by alcohol dehydrogenase to oxidize NADH to ${ NAD }^{ + }$ and it also reduces acetaldehyde to ethanol.
So the correct answer to the above statement is ‘All of the above’.

Note: During this fermentation process, yeast is usually used as a bio-culture and solution of monosaccharide (raw materials) because of the culture media for the assembly of beverages. Within the alcoholic fermentation process, yeast generally carries out the aerobic fermentation process, but it's going to also ferment the raw materials under anaerobic conditions. Within the absence of oxygen, alcoholic fermentation occurs within the cytosol of yeast.