Question

In the process of respiration, the largest amount of energy is produced during

• A. Anaerobic respiration.
• B. Krebs cycle and oxidative phosphorylation.
• C. Glycolysis.
• D. None of the above.

Answer 1

The correct option is B Krebs cycle and oxidative phosphorylation.

During the process of respiration, glucose is broken down into pyruvic acid during the process of glycolysis. No oxygen is consumed nor any molecule of carbon dioxide is released in the process. The pyruvic acid molecule can be completely oxidised to carbon dioxide and water or incompletely oxidised to produce ethanol and carbon dioxide (alcohol fermentation) or lactic acid (lactic acid fermentation). The process of glycolysis occurs in cytoplasm, like the reactions of fermentation. For the process of aerobic respiration pyruvic acid needs to be transported to mitochondria. In the process of glycolysis only 2 molecules of ATP are produced. Maximum energy is released, when the reduced coenzymes produced in the process of Krebs cycle are oxidised in the process of oxidative phosphorylation in electron transport chain.