Question

what are the different ways in which glucose is oxidised to provide energy in various organisms.

Answer 1

At first glucose (6 carbon molecules) is broken in the cytoplasm of cells of all organisms. This process yields a 3 carbon molecule compound called pyruvate.
Further break down of pyruvate takes place in different manners in different organisms.

1. Anaerobic Respiration
This process takes place in absence of oxygen, e.g. in yeast during fermentation. In this case pyruvate is converted into ethanol and carbon dioxide.
2. Aerobic Respiration
In aerobic respiration, breakdown of pyruvate takes place in presence of oxygen to give rise 3 molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than anaerobic respiration.
3. Lack of Oxygen
Sometimes, when there is lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid (3 carbon molecule compounds). Formation of lactic acid in muscles causes cramp.

Answer 2

In lower organism glucose is breakdown in the absence of oxygen.
forming alcohol or lactic acid with less amount of carbon dioxide.

the glucose is not completely breakdown in this process called as anaerobic .


when glucose is breakdown in presence of oxygen then it breakdown into more amount of carbon dioxide.

in this glucose is completely breakdown so it is called as aerobic respiration.