Explain the oxygen cycle in detail.
After carbon, oxygen is one of the most abundant elements on earth. About 21% of our air is composed of oxygen. Plants release oxygen into the atmosphere as a by-product during the process of photosynthesis. Plants and animals use oxygen during respiration (plants release more amount of oxygen when compared to the amount that they use for respiration). Plants and animals release carbon dioxide during respiration and this is again used up by the plant during photosynthesis.