Where does photosynthesis occur in plant ?

Photosynthesis takes place in the leaves but photosynthesis is also reported in the stems in some special conditions. It is  both light independent and light dependent. The light dependent process uses light that has been absorbed by the thylakoids to convert into  chemical energy. This chemical energy is used by the CO2 for the synthesis of carbohydrates. 

Chloroplasts are green plastids present in plant cells . The chloroplasts are  the site of photosynthesis in green plants or photoautotrophs. The leaves are the site of photosynthesis . Inside the leaves, chloroplast is generally present in mesophyll cells along their walls.

Within the chloroplast there is a membranous system  in which a structure like the pile of coins is present called grana, the stroma lamellae and the fluid that is present in the chloroplast called  stroma.

👌👌Remember - The light and dark reaction of photosynthesis takes place in Grana and Stroma respectively.

The membrane system is responsible for synthesizing light energy for the synthesis of ATP and NADPH. In stroma all the enzymatic reactions needed for formation of   ATP and NADPH takes places.The reaction in which light energy is absorbed by grana to synthesis ATP and NADPH is called  Light reaction.  Light reaction or photochemical phase includes the Light absorption, Water splitting, Oxygen release and the Formation of ATP and NADPH. Light reaction is followed by the dark reaction  of photosynthesis in which carbohydrates or glucose is synthesised. During a dark reaction , light is not necessary. Dark reaction is also called the biosynthesis phase. 

Pigments involved in Photosynthesis – Chromatographic separation  of leaf pigments reveals that Maximum absorption by chlorophyll a occurs in blue and red regions having higher rate of photosynthesis. So, chlorophyll a is the chief pigment. Other thylakoid pigments like chlorophyll b, xanthophyll and carotenoids are called accessory pigments that absorb light and transfer energy to chlorophyll a and protect them from photo-oxidation.

Photosynthetic Active Radiation (PAR)

The surface of the leaf absorbs the blue and red wavelengths while the green light is absorbed by the internal part of plants Or leaves.This light that is absorbed by the chloroplasts used in photosynthesis and the conversion of energy. All the visible wavelengths are absorbed by the leaf but red, blue and green are the most important for photosynthesis. The light spectrum used by plants is known as Photosynthetic Active Radiation (PAR) ranging between 400 and 700 nm.out of total solar radiation only 10 percent are used by the plant as Photosynthetic Active Radiation (PAR).