Question

What are the different ways in which glucose is oxidized to provide energy in various organisms.

Answer 1

Glucose is the important energy source for all the organisms. The nutrients which are consumed are converted into carbohydrates in which glucose is the main ingredient. The glucose is oxidized and provides energy to the organism.

Complete answer:
The breakdown of glucose which involves two processes. In the first one, glucose is broken down three carbon molecules pyruvate ${C_3}{H_4}{O_3}$ . Now in the second step the pyruvate is further broken down into energy.The ways in which energy is broken down are as follows:
(I)Aerobic respiration: This is the first step in which pyruvate is broken down into the components which are carbon dioxide and water and along with it energy is also released. Generally this occurs in mitochondria of the cells. In aerobic respiration breakdown of pyruvate takes place in presence of oxygen.
(II)Anaerobic respiration: In anaerobic respiration breakdown of pyruvate takes place in presence of oxygen which gives 3 molecules of carbon dioxide and water as a resultant product. And finally pyruvate is converted into ethanol and carbon dioxide.In anaerobic respiration the entire process takes place in the absence of oxygen.
Let us understand it with the help of examples such as in yeast during fermentation.
(III)Lack of oxygen: When there is lack of oxygen in our body, or we can say that mainly vigorous activity, in our muscles, pyruvate is converted into lactic acid with nothing other than three molecules of carbon compounds. The formation of lactic acid in muscles causes cramp.

Note: The release of energy in aerobic respiration is much more than the energy release in anaerobic respiration. Summarizing up we can say that glucose is converted into pyruvate with the help of cytoplasm then: In the presence of oxygen pyruvate is converted into carbon dioxide, water and energy.In lack of oxygen pyruvate is converted into lactic acid and energy.In absence of oxygen pyruvate is converted into ethanol, carbon dioxide and energy.