What gas is primarily obtained from the environment during respiration?

During respiration, the primary gas obtained from the environment is oxygen. This process, known as aerobic respiration, occurs in living organisms where oxygen is utilized to break down glucose to produce energy (ATP), along with carbon dioxide and water as byproducts. Oxygen is essential for this energy production, and it is absorbed by the lungs in mammals or through other respiratory structures in different organisms.

In the context of bodily functions, cells require oxygen to perform aerobic cellular respiration, which is a highly efficient process for energy production compared to anaerobic respiration that occurs when oxygen is not available.

While nitrogen is a significant component of the Earth's atmosphere, it does not play a direct role in the respiration process. Carbon dioxide, although a product of respiration, is not the gas taken in during the process. Hydrogen is not directly involved in respiration as a gas; rather, it forms part of molecules like glucose. Therefore, oxygen stands out as the essential gas required from the environment during respiration.