In the following flow chart, replace the symbols a,b,c and d with appropriate terms, Briefly explain the process and give any two application of it.

Explanation

The metabolic pathway given in the figure is fermentation. The products marked as a,b,c and d represents
a-Glyceraldehyde 3 phosphate, `" "` b-Phosphoenol pyruvic acid
c-Ethanol, `" "` d-Lactic acid

The fementation is of two types
(i) Alcohol Fermentation in Yeast Fermentation is an incomplete oxidation of glucose under anaerobic condition. Alcohol fermentation in yeast occurs in 2 sets of reaction thus, converting pyruvic acid into ethanol and `CO_(2)`
A . In the first step, pyruvic acid is decarboxylated (equation I) resulting in the formantion of acetaldehyde and `CO_(2)`
`2CH_(3)underset("Pyruvic acid")(COCOOH)overset("Pyruvic decarboxylase")rarrunderset("Acetaldehyde")(2CH_(3)CHO)" "....(i)`
B. In the second step acetaldehyde is reduced to alcohol by `NADH_(2)` (equation (ii))
`" "....(ii)`
(ii) Lactic Acid Fermentation in Muscles
In animal tissue muscles, during exercise, when oxygen is inadequate for cellular respiration pyruvic acid is reduced to lactic acid by lactate dehydrogenase. The reducing agen is `NADH+H^(+)` which is reoxidised to `NAD^(+)` in the subsequent process.
Two applications of fermentation process are
(i) It helps in manufacture of ethyl alcohol.
(ii) It also helps in curdling of milk to make curd aided by bacteria Lactobacillus.