CBSE Class 10 Answered

Anaerobic respiration in humans is as follows:

• Glucose --> Lactic Acid

And in Yeast:

• Glucose --> 2 Carbon Dioxide + 2 Ethanol

In brewing, anaerobic respiration is very important as it turns the wort into beer using yeast. Yeast is used in brewing in order to make the carbon dioxide and ethanol. These are made by anaerobic respiration even if there is a good supply of oxygen. This process is called fermentation, and is defined as the breakdown of sugars by bacteria and yeasts by respiration without oxygen.

The first step of fermentation in brewing is where complex sugars or polysaccharides are broken down into monosaccharides, for example glucose by yeast. The glucose is then broken down into ethanol and carbon dioxide in a decomposition reaction, where energy is also produced – although there is less energy produced than in aerobic respiration. This step is called ethanol fermentation, whereas lactic acid fermentation is another form of anaerobic respiration which happens in animal cells in the absence of oxygen.