Write two different ways in which glucose is oxidised to provide energy in human body. Write the products formed in each case. (Delhi 2019)

Solution :


The most important source of energy for all living things is glucose.
The most important carbohydrate that comes from the food we eat is glucose. To give the body energy, glucose is oxidised.
The different processes by which glucose is broken down are mentioned below.

Aerobic Respiration

Aerobic respiration occurs only in the presence of oxygen.
In aerobic respiration, there are three specific processes, which are glycolysis, the Krebs cycle and the electron transport chain (oxidative phosphorylation).

This process involves the conversion of glucose to pyruvate during glycolysis, and the same pyruvate also generates energy along with carbon dioxide and water.

Anaerobic Respiration

In the absence of oxygen, anaerobic respiration takes place.
Without oxygen, two different types of fermentation can take place.

Alcoholic Fermentation

In yeast, alcohol is produced through the process of fermentation. Because there is no oxygen present, only glycolysis can take place, and glucose is converted to pyruvate at the end of the process.
The fermentation of alcohol causes the pyruvate to become ethyl alcohol.

Fermentation of lactic acid

Because there isn’t enough oxygen in the system, lactic acid fermentation takes place.
Lactic acid is produced and accumulated in anaerobic conditions in the muscles, where it occurs.

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