Question

The puffed-up appearance of dough is due to fermentation by bacteria. Identify the gas liberated during the process.
A. Methane
B. Carbon dioxide
C. Hydrogen sulphide
D. Ammonia

Answer 1

Hint: Fermentation is the process of anaerobic respiration performed by bacteria. In this process, bacteria convert carbohydrate into alcohol and releases the byproduct. This gas is also produced by animals during the time of respiration. It is a gas that also leads to global warming.

Complete answer: When the dough is prepared, Yeast or bacteria is added to it to make the dough puffy and porous. The dough becomes puffy due to the presence of carbon dioxide liberated by bacteria during fermentation. Fermentation is anaerobic respiration performed by bacteria in the absence of oxygen. In this process, the bacteria convert carbohydrate into ethanol and the byproduct is released during the reaction called the carbon dioxide. Saccharomyces cerevisiae is a species of yeast which is used in baking, winemaking and brewing that’s why Yeast is also known as the ‘Brewer’s yeast’. Methane is produced by the gobar gas. Biogas is produced from cattle dung. Biogas primarily consists of carbon dioxide and methane. This gas is produced from raw materials like manure, agriculture wastes, etc. Yeast is a single-celled, eukaryotic microorganism. It belongs to the kingdom Fungi. Yeast keeps the digestive system healthy and in balance.
Hence, the correct answer is option B.

Note: It is believed that Saccharomyces cerevisiae is originally isolated from the skin of grapes. It has been used by the people since ancient times. Yeast is helpful in treating diarrhoea. Biogas is inflammable and it is used in villages for cooking purposes.