. What is light reaction ? What are the steps involved in it ?
A. . 1) Light reaction is the first stage in photosynthesis. .
2) Reaction of photosynthesis that takes place in presence of light are called light reactions or photochemical reactions.
3) The light reaction takes place in chlorophyll containing thylakoids called grana of
4) Light reaction occurs in several steps.
Step -1 It is called oxidation of chlorophyll. In this process chlorophyll is exposed to light absorbing photons and become activated.
Step - II: It is known as photolysis. The oxidised energy is used to splitting the water molecule. Photo means light, lysis means break down.
1) This is called reduction action. Here OH- ions goes to reduction and forms water molecule.
2) H* ions are used to form ATP, and NADPH2
3) These are known as assimilatory powers which are known as end products of light reactions.