How does the oxygen in the atmosphere help protect and support life on Earth?

Oxygen is a vital gas which is the requirement of every single organism living on this planet. Oxygen is used by living organisms in the process respiration for the release of energy from food molecules such glucose. This energy is used by the cell in different processes and activities. The energy which is released are present in the form of Adenine tri phosphate (ATP). In respiration process, carbondioxide is produced and released in the atmosphere which is used by the plants in the process of photosynthesis. In photosynthesis, oxygen is produced which is released in the atmosphere and use by the organisms again for respiration.