Question

it was the final mile of the city marathon when 22 - year - old runner liam suddenly collapsed. paramedics rushed to his side - his breathing was shallow, his pulse weak, and his skin slightly flushed, not bluish as one might expect with oxygen deprivation. he was quickly taken to the emergency department. doctors ran tests. his oxygen levels were normal, but he was clearly not using that oxygen effectively. liams cells seemed to be suffocating - even though oxygen was plentiful in his bloodstream. his blood ph was dropping, lactic acid levels were rising, and his muscles were failing. something was blocking his bodys ability to use energy. dr. singh, the attending physician, noticed a faint smell of bitter almonds on liams breath - a clue that pointed her toward a terrifying possibility: cyanide poisoning. cyanide is a chemical that interferes with the production of atp during the final stage of cellular respiration. question 18 what role does oxygen normally play in cellular respiration? a it is required for the formation of nearly 40 atp molecules b it provides carbon for glucose molecules c it removes carbon dioxide from the blood d it breaks down atp into adp

Explanation:

In cellular respiration, oxygen is the final electron acceptor in the electron - transport chain. This process is crucial for the production of a large amount of ATP. Glycolysis produces a small amount of ATP (about 2 ATP per glucose molecule), and the citric acid cycle also produces a limited amount (about 2 ATP per glucose molecule). The majority of ATP (around 34 - 36 ATP per glucose molecule) is produced in the electron - transport chain, where oxygen is required.

• Option a: In aerobic cellular respiration, about 36 - 38 ATP molecules are produced per glucose molecule, and oxygen is required for the electron - transport chain which is responsible for the production of the majority of these ATP molecules. So, oxygen is required for the formation of nearly 40 ATP molecules.
• Option b: Carbon for glucose molecules comes from carbon fixation (in plants, usually from \(CO_2\) in the atmosphere) or from dietary sources (in animals). Oxygen does not provide carbon for glucose molecules.
• Option c: The removal of carbon dioxide from the blood is mainly the function of the lungs (exhalation) and the bicarbonate buffering system in the blood, not the role of oxygen in cellular respiration.
• Option d: ATP is broken down into ADP and inorganic phosphate (\(P_i\)) to release energy for cellular work. This is an independent process from the role of oxygen in cellular respiration. Oxygen is involved in ATP synthesis, not its breakdown.

Answer:

a. It is required for the formation of nearly 40 ATP molecules