Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which gas is crucial to all the body's cells?

1. Carbon dioxide

2. Nitrogen

3. Hydrogen

4. Oxygen

The correct answer is: Oxygen

Oxygen is crucial to all the body's cells because it plays a vital role in cellular respiration, a process that converts nutrients into energy. Cells require this energy to carry out functions essential for survival, growth, and repair. Oxygen is used by cells to break down glucose in the presence of other nutrients, producing adenosine triphosphate (ATP), which is the primary energy carrier in all living organisms. While carbon dioxide, nitrogen, and hydrogen are important in various biochemical processes, they do not fulfill the same essential role as oxygen in cellular respiration. Carbon dioxide is a waste product of respiration that needs to be expelled from the body, nitrogen is mostly inert with limited biological function except in specific compounds, and hydrogen is a component of many organic molecules but not directly utilized as a gas by cells. Therefore, oxygen stands out as the gas that is crucial and directly required by all cells for their metabolic processes.