The Earth's atmosphere would have little or no oxygen. A by-product of photosynthesis is oxygen. Photosynthesis is the process by which green plants use energy from the sun to make their own food in the leaves. The process uses sun light, water and carbon dioxide to yield oxygen and simple sugars. The simple sugars are stored in form of starch for future use by the plants, while oxygen is either used for cellular respiration or released to the atmosphere. The process of photosynthesis adds oxygen to the atmosphere and uses carbon dioxide from the atmosphere.
Humans even though i dont believe in evolution but that is the scientific answer
<span>The answer is free-market. One view is that a free market is a framework in which the costs for products and enterprises are controlled by the open market and purchasers, in which the laws and strengths of free market activity are free from any intercession by an administration, value setting syndication, or other specialist.</span>
