Question

ADP + Pi = ATP in grana is called as
A. Phosphorylation
B. Oxidative phosphorylation
C. Photophosphorylation
D. Photolysis

Answer 1

The chloroplast has two main parts which are the stroma and the grana. Grana is also known as the thylakoid which is the unit of granum. The plural form of grana is granum which is a collection of various grana stacked together.

Complete answer:
Phosphorylation –
Phosphorylation refers to the addition of the inorganic phosphorus molecule to AMP or ADP to form the ADP or ATP respectively. Phosphorylation is of three types mainly which can be glucose phosphorylation, protein phosphorylation, and oxidative phosphorylation depending upon the conditions.
Oxidative phosphorylation –
Oxidative phosphorylation is a type of phosphorylation. Phosphorylation refers to the addition of the inorganic phosphorus molecule to AMP or ADP to form the ADP or ATP respectively. During oxidative phosphorylation, ATP is formed as a result of the transfer of the electrons from different compounds to oxygen via electron carriers. This process usually occurs in the mitochondria of the cell.
Photophosphorylation –
Photophosphorylation is the type of phosphorylation that occurs during the presence of light. Phosphorylation refers to the addition of the inorganic phosphorus molecule to AMP or ADP to form the ADP or ATP respectively. This process occurs in the grana of the chloroplast during the light reaction.
Photolysis –
The word photolysis is formed up of two words, photo meaning light and lysis meaning breaking. Therefore, photolysis is the hydrolysis of the splitting of the water molecule in the presence of light. The breakdown of water molecules releases protons and electrons required for the process of photosynthesis.
Thus, based on the above information we can conclude that ADP + Pi = ATP in grana is called Photophosphorylation.

Hence, the correct answer is option (C).

Note: The light reaction of photosynthesis occurs in the grana and the dark reaction occurs in the stroma. The light reaction is the light-dependent process whereas the dark reaction is the light-independent process.