What are different ways in which glucose is oxidised to provide energy in various organisms?
A. Breaking down of glucose involves two processes. In the first step, it is broken into three carbon molecules called pyruvate. The pyruvate is further broken down into energy in following different ways in various organisms.
1) Aerobic respiration : In this case pyruvate is broken down into water and carbon dioxide along with release of energy. It commonly occurs in mitochondria of cells.
2) Anaerobic respiration in yeast : In yeast cells during fermentation pyruvate is converted into ethanol and C02 in the absence of 02.
3) Anaeorbic respiration in muscles: Due to lack of oxygen, eg. during vigorous running or exercise, in human muscles, pyruvate is converted to lactic acid.