The process by which plants manufacture their own food from inorganic substances with the help of solar energy is known as photosynthesis. The green plants produce organic matter by drawing nutrients and water from the soil, carbon dioxide from the atmosphere and sun's radiant energy. The process of photosynthesis is made possible by the presence of a green pigment called chlorophyll in the leaves of the plants. The green plants are the primary producers and are called autotrophs. They become the food of the herbivores which in turn become the food of carnivores. The significance of photosynthesis is that, through it, the food-chain begins and continues and the life process goes on.