Which gas in the atmosphere is essential for respiration?

The gas essential for respiration in the atmosphere is oxygen (O₂).

Explanation

• Respiration Process:
  Oxygen is a critical component for the process of cellular respiration, where it is used to break down glucose molecules in cells to produce energy in the form of ATP (adenosine triphosphate). This process occurs in the mitochondria of cells.
• Role of Oxygen:
  During respiration, oxygen acts as the final electron acceptor in the electron transport chain, enabling the efficient production of energy.
• Availability in the Atmosphere:
  Oxygen makes up about 21% of the Earth's atmosphere, which is sufficient to support the respiration needs of humans, animals, and many other organisms.
• Importance:
  Without oxygen, aerobic organisms cannot generate the energy needed for survival, leading to reliance on less efficient processes like anaerobic respiration in its absence.

Fun Fact About Respiration

While oxygen is essential for respiration, plants also play a crucial role in replenishing atmospheric oxygen through the process of photosynthesis. This maintains the balance of gases in the atmosphere.