What are the two main ways oxygen is consumed and carbon dioxide is produced?

The two primary processes that consume oxygen and produce carbon dioxide are cellular respiration and combustion. Cellular respiration is a biological process occurring in living organisms, where cells break down glucose and other organic molecules using oxygen to release energy, producing CO₂ and water as byproducts. This process is essential for life, providing the energy needed for all cellular activities. Combustion, or burning, is a chemical reaction where organic materials combine rapidly with oxygen, releasing energy as heat and light while producing CO₂. Both natural fires and human activities like burning fossil fuels contribute to combustion. Together, these processes complement photosynthesis in the carbon-oxygen cycle, maintaining atmospheric balance when in equilibrium.