Question

Out of 36 ATP molecules produced per glucose molecule during respiration

• A. 2 are produced outside glycolysis and 34 during respiratory chain
• B. 2 are produced outside mitochondria and 34 inside mitochondria
• C. 2 during glycolysis and 34 during Krebs cycle
• D. all are formed inside mitochondria.

Answer 1

The Correct Option is B

The process of ATP (Adenosine Triphosphate) generation during cellular respiration involves multiple stages: glycolysis, the Krebs cycle (also known as the citric acid cycle), and the electron transport chain, which is part of oxidative phosphorylation.

Here is a breakdown of ATP production at each stage:

1. Glycolysis: This process occurs in the cytoplasm (outside the mitochondria) and results in a net gain of 2 ATP molecules per glucose molecule.
2. Krebs Cycle and Electron Transport Chain: These processes occur inside the mitochondria. The Krebs cycle itself directly produces 2 ATP molecules per glucose molecule (considering two turns of the cycle per glucose). However, the major ATP yield comes from the electron transport chain, which produces approximately 32 ATP molecules per glucose through oxidative phosphorylation.

Therefore, the overall ATP yield from the complete oxidation of one glucose molecule is 36 ATP. We can categorize these as:

• 2 ATP are produced outside the mitochondria during glycolysis.
• 34 ATP are produced inside the mitochondria (2 from Krebs cycle and 32 from Electron Transport Chain).

This logic aligns with the correct answer: "2 are produced outside mitochondria and 34 inside mitochondria."

Let's rule out the incorrect options:

• 2 are produced outside glycolysis and 34 during respiratory chain: This option incorrectly attributes only the electron transport chain for the production of 34 ATP without considering the Krebs cycle.
• 2 during glycolysis and 34 during Krebs cycle: This is incorrect because the Krebs cycle alone does not produce 34 ATP; it produces only 2 ATP. The remaining 32 ATP are from the electron transport chain.
• All are formed inside mitochondria: This is incorrect because the initial 2 ATP from glycolysis are produced in the cytoplasm, not inside mitochondria.