Question

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.

Answer 1

Pathways of anaerobic respiration:

Anaerobic respiration involves glycolysis followed by the breakdown of pyruvate to ethanol and $C{O}_2$ (in yeast) or lactic acid (bacteria or animal skeletal muscles).

$\bullet$ Labelling a - Glyceraldehyde-3-phosphate

$\bullet$ Labelling b - Phosphoenol pyruvic acid

$\bullet$ Labelling c - Ethanol

$\bullet$ Labelling d - Lactic acid

Anaerobic respiration:

The process shown in the given flowchart is depicting different pathways of anaerobic respiration.

$\bullet$ During anaerobic respiration, a cell does not have sufficient oxygen for the complete breakdown of glucose to $C{O}_2$.

$\bullet$ Thus, the fate of pyruvic acid formed as the end product of glycolysis differs from organism to organism.

$\bullet$ In yeast cells, under anaerobic conditions, pyruvic acid is converted into ethanol and CO2 in a two step process by the oxidation of NADH to NAD+. This process is also called fermentation.

$\bullet$ In bacteria and animal skeletal muscles, under anaerobic conditions, pyruvic acid is converted into lactic acid by the enzyme lactate dehydrogenase.

Applications of anaerobic respiration:

$\bullet$ Barley, wheat and fruits juices are fermented for the commercial production of wine, beer and other alcoholic drinks.

$\bullet$ Idli, dosa, cheese, and cake are also produced by fermentation. The large holes observed in these food items are due to the production of $C{O}_2$ gas by anaerobic respiration of Saccharomyces cerevisiae.

Summary