If there is no photosynthesis, it is merely a matter of time before the world?s oxygen supply is completely exhausted. During photosynthesis, plants use carbon dioxide, water and light from the sun to produce glucose and oxygen, which is emitted into the air as a waste product. Humans inhale oxygen from the air.
Since plants use carbon dioxide from the air and release oxygen into the air, the world?s ecosystem is well-managed. Without photosynthesis, there would be an excess of carbon dioxide in the environment, thereby creating air pollution. This pollution is detrimental to the health of human beings.
Another benefit of photosynthesis is glucose. Humans cannot make glucose by themselves. Plants store excess glucose as carbohydrates in their stems, leaves or roots. Carbohydrates happen to be one of the food categories needed by human beings. Carbohydrates are the source of energy of humans.
Photosynthesis is also the reason for the existence of fossil fuels, which were created millions of years ago. Humans use these fuels as industrial energy sources, like petroleum, natural gas and coal. Thus, without photosynthesis in plants, human beings would lack a source of oxygen, energy derived from food, and energy for industrial and daily use.