Structure of chloroplastsThe outer layer is called as chloroplast envelope ( double membrane )

The fluid in chloroplast is called as stroma

The network of flattened sacs in the stroma is called as thylakoids.

Grana are formed when many thylakoids are stacked together like a pile of coins

Chlorophyll is found in each granum.

Starch grains (temporary store of products of photosynthesis) are also found in stroma

What are the advantages of grana?

Large surface area for light absorption

Economy of space