Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems, etc. The parts of a typical leaf include the upper and lower epidermis, the mesophyll, the vascular bundle(s) (veins), and the stomates. The upper and lower epidermal cells do not have chloroplasts, thus photosynthesis does not occur there. They serve primarily as protection for the rest of the leaf. The stomates are holes which occur primarily in the lower epidermis and are for air exchange: they let CO2 in and O2 out. The vascular bundles or veins in a leaf are part of the plant's transportation system, moving water and nutrients around the plant as needed. The mesophyll cells have chloroplasts and this is where photosynthesis
The net overall chemical reaction of plant photosynthesis can be described as below.
The photochemical reaction in plants occurs in grana part of the chlorophyll. This reaction is also called Hill Reaction. In the reaction water breaks down to form hydrogen ion and electron. Energy comes from sunlight for photosynthesis of water. At the end of the process, ATP is formed from ADP & P.
Dark Chemical Reaction
The Dark Chemical Reaction occurs in the stroma of chlorophyll. In this reaction redction of carbon dioxide takes place and sugar/starch are formed. This reaction also referred as Calvin Benson Cycle.