Question

Photo phosphorylation event take place in:
A. Stroma
B. Stroma lamellae
C. Grana lamellae
D. $B$ and $C$ both

Answer 1

It is also known as fret channels. It connects the thylakoids of different grana. This part of chloroplast is essential to increase the efficiency of photosynthesis by keeping grana at distance so that they don’t clump together. It has a photosystem- $1$ where the photo phosphorylation reaction takes place. The electron released from it begins to move to different acceptors to produce a proton motive force which powers the conversion of ADP to ATP.

Complete answer:
Option A Stroma: Stroma is a type of fluid filling the inner space of the chloroplasts which encircle the grana and thylakoids. They also include chloroplast DNA, starch, and ribosomes, as well as Calvin cycle enzymes. Their main role is in Light reaction and Dark reaction of photosynthesis. Here Photo phosphorylation does not take place
Option A is incorrect
Option B Stroma lamellae: The region of stroma that connects the thylakoid stacks are known as stroma lamellae. In this region cyclic photophosphorylation takes place. Photosystem- $1$ present in stroma lamellae releases a high energy electron which flows down in a cyclic pathway. This helps to produce a proton motive force, pumping H+ ions across the membrane and producing a concentration gradient. This gradient can be used to power ATP synthase for the production of ATP.
Option B is correct
Option C Grana lamellae: The region between the grana is called as grana lamellae. It is present in between the grana. It is present in the light reaction region. They aid in light reaction of photosynthesis. Here no photo phosphorylation reaction takes place.
Option C is incorrect
Option D $B$ and $C$ both: Since Grana lamellae does not aid in photophosphorylation $C$ cannot be right.
Option D is incorrect

Therefore, Option B is the correct answer.

Note:
Photo phosphorylation is a process of converting ADP into ATP molecules with the help of light energy from photosynthesis. It is the process of adding the phosphate group to an ADP molecule in the presence of light in order to produce energy-rich ATP molecules. There are two types of Photophosphorylation- Cyclic and Non cyclic.