An individual breathing ambient air (21% oxygen) at atmospheric pressure at rest will maintain an arterial oxygen pressure of 90 mmHg and a tissue oxygen pressure of 55 mmHg. However, during periods of extreme exercise, the pressure of oxygen in tissues can drop dramatically, causing a shift from aerobic respiration to anaerobic respiration. The production of which of the following molecules will cease during this transition?
- Pyruvate
- Water
- Adenosine triphosphate
- None of the above
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Oxygen is necessary to aerobic respiration in mitochondria, as oxygen is the final electron acceptor of the electron transport chain. However, each of the products listed can be produced via anaerobic respiration.
a) Incorrect: Pyruvate is a product of glycolysis and can be converted into lactic acid via anaerobic pathways.
b) Incorrect: Water is a product of glycolysis, as well as other metabolic pathways.
c) Incorrect: Adenosine triphosphate (ATP) is a product of glycolysis
d) Correct: None of the above will cease being produced.
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