Question

$2H_{2}O\to 4H^{+}{O}_2+4e^{-}$ Based on the above equation,answer the following questions:
a. Where does this reaction take place in plants?
b. What is the significance of this reaction?

Answer 1

Splitting of water:

The reaction given in the question is the splitting of water or the photolysis of water. It occurs on the inner side of the thylakoid membrane. Replenishing of electrons in the photosystem II is achieved by splitting of water.

Significance of splitting of water:

• Splitting of water in the light reaction produces hydrogen ions, electrons, and oxygen gas.
• Hydrogen ions create the proton gradient across the thylakoid membrane. This gradient is the driving force for the synthesis of ATP.
• Oxygen gas produced is either evolved out or utilized by the plant itself for respiration.
• Water also acts as a reducing agent. The hydrogen ions produced are used for reducing NADP to NADPH.
• The electrons are used to replenish the electrons in photosystem II.