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

(N/A) The symbols in the flow chart represent the steps of glycolysis and fermentation:
$a = \text{Glucose-6-phosphate}$
$b = \text{Phosphoenolpyruvate (PEP)}$
$c = \text{Ethanol}$
$d = \text{Lactic acid}$
Explanation: The process shown is glycolysis followed by anaerobic respiration (fermentation). Glycolysis is the breakdown of glucose into pyruvic acid, occurring in the cytoplasm. Under anaerobic conditions, pyruvic acid is converted into either ethanol and $CO_2$ (in yeast) or lactic acid (in muscle cells/bacteria).
Applications:
$1$. Brewing Industry: Used in the production of alcoholic beverages like wine and beer.
$2$. Baking Industry: Used in bread making where $CO_2$ released makes the dough rise.