Which two gases make up more than 95 percent of an inhaled breath?

The correct response indicates that oxygen and nitrogen are the predominant gases in the air we breathe. Inhaled air is typically composed of approximately 21% oxygen and around 78% nitrogen, which together constitute more than 95% of the atmosphere we breathe.

Oxygen (O2) is essential for cellular respiration, where it is used to produce energy in the form of ATP in the body's cells. Nitrogen (N2), on the other hand, is largely inert and does not participate in metabolic processes in the human body, but it plays a crucial role in maintaining atmospheric pressure and facilitates the stability of the respiratory system.

While carbon dioxide and water vapor are constituents of exhaled breath, they do not make up a significant portion of inhaled air. Other gases like hydrogen (H2), helium (He), and argon (Ar), while present in trace amounts in the atmosphere, do not constitute a significant portion of the inhaled breath either. This highlights the unique and essential role of nitrogen and oxygen in respiration and overall human physiology.