Which among the following structures is the stacking up of grana like the piles of coins in chloroplast?

The correct answer is Thylakoids.

Key Points

• Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria.
• They are the site of the light-dependent reactions of photosynthesis.
• Thylakoids are organized into stacks called grana (singular: granum).
• Each granum looks like a stack of coins, where each "coin" is a thylakoid.

Additional Information

• Stroma: The stroma is the fluid-filled space surrounding the grana inside the chloroplast. It contains enzymes for the light-independent reactions (Calvin cycle) of photosynthesis.
• Inner membrane: The inner membrane of the chloroplast is the boundary that surrounds the stroma and the thylakoid system. It plays a role in the regulation of the passage of molecules into and out of the chloroplast.
• Stroma lamellae: The stroma lamellae are extensions of the thylakoid membrane that connect different grana, facilitating the movement of molecules between grana.