The raw materials for photosynthesis are carbon dioxide, water and other materials like minerals extra.
Carbon dioxide-it is released into the atmosphere during cellular respiration of organisms and enters the leaf through stomata. Stomata are tiny pores present on the surface of leaves through which massive amount of gaseous exchange takes place. Apart from this surface of stems, leaves and roots also contribute in the gaseous exchange.
Water-it is absorbed by roots from the soil and transported upward through xylem to the leaves and then to the photosynthetic cells . These water molecules split in the presence of sunlight to form hydrogen and oxygen. This is called photolysis of water. Hydrogen ions are used to reduce carbon dioxide and oxygen is given off as by product.
Other materials-mineral nutrients like nitrogen, phosphorus, iron and magnesium are also taken up from the soil. Nitrogen is an essential element used in the synthesis of proteins and other compounds. It is taken up in the form of inorganic nitrates (or nitrites ) or as organic compounds prepared by symbiotic bacteria like rhizobium from atmospheric nitrogen.