Question

Which is the correct order for the processes involved in aerobic cellular respiration?

• A. Krebs cycle, glycolysis, electron transport chain.
• B. Glycolysis, Krebs cycle, electron transport chain.
• C. Glycolysis, fermentation, electron transport chain.
• D. Fermentation, Krebs cycle, electron transport chain.
• E. Glycolysis, electron transport chain, fermentation.

Answer 1

Answer: (B)

Glycolysis, Krebs cycle, electron transport chain.

The process of harvesting chemical energy for metabolic activities in form of ATP by oxidising the food molecule is called respiration. The chemical bond energy stored in various molecules is decomposed or oxidised in this process. The most common substrate used in this pathway is glucose.

Glucose is first converted to 2 molecules of pyruvate by a pathway known as Glycolysis. The pyruvate formed is converted to Acetyl-CoA which then enters Krebs cycle. In Krebs cycle, Acetyl-CoA is oxidised to form CO₂, ATP, NADH, FADH₂. NADH and FADH₂ are used as the reducing power in Electron Transport Chain or ETC to oxidise various enzymes and co-enzymes in ETC which results in synthesis of ATP.

Hence, the correct order for the processes involved in aerobic cellular respiration is Glycolysis, Krebs cycle, Electron transport chain.

So, the correct answer is 'Glycolysis, Krebs cycle, Electron transport chain'.