What Is The Importance Of Oxygen And Carbon Dioxide?

Oxygen is necessary for living creatures to respire with out we can't release energy which we needed.
Carbon dioxide is important for plants in the process of photosynthesis. If they don't have this then who would release oxygen in air?

Oxygen is the key ingredient in the human body metabolism is the first needs of human life activities.Carbon dioxide is an indispensable raw material for photosynthesis in green plants, greenhouse carbon dioxide, commonly used as fertilizer.

The production of carbon dioxide in the biosphere: Biological → carbon dioxide respiration and microbial respiration, including plant and animal remains and feces of animals and plants in the decomposition of organic matter, so as to continuously release carbon dioxide into the air, the earth is estimated that 90% of carbon dioxide by microorganisms Life activities.