Photosynthesis is a plant process that converts light energy to chemical energy and stores it in plant sugars. Plants use light energy from the sun, CO2 (carbon dioxide), and H2O (water) to make sugar. The process of photosynthesis uses chlorophyll, the green pigment in plants. A leaf may be considered a solar collector full of photosynthetic cells.
Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems, etc.The upper and lower epidermal cells (leaf skin layer) does not have chlorophyll. They protect the rest of the leaf, and have holes, stomates, which are on the underside of the leaf and are for air exchange: they let CO2 in and O2 out.
Chlorophyll looks green because it absorbs red and blue light, so we do not see these unavailable colors. It is the green light which is NOT absorbed that reaches our eyes, making chlorophyll appear green. The energy from the red and blue lights are absorbed and used to do photosynthesis. Not all chlorophylls appear to be green, but these are the predominate ones. In the autumn, when the green chlorophyll fades, then the reds, yellows and orange chlorophylls can be seen in the autumn leaves.
Water enters the root and is carried up to the leaves through plant cells known as xylem.
The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf to be used by the
chlorophyll, and the products of photosynthesis, plant sugars and oxygen, leave the leaf.
Sugars (sap) move in the phloem cells to all parts of the plant to feed it. Oxygen is released through the stomates. Water is also left over and escapes from the leaf stomates, called transpiration.