Organelles that act like a digestive
system which takes in nutrients, breaks
them down, and creates energy rich
molecules for the cell

Mitochondria

Explanation:

As monomers(e.g. glucose,galactose...) pass through cell membrane mitochondria takes them and breaks them down, when it breaks down the monomers, energies hidden in the monomers releases. Mitochondria takes them and put them in ATP between the phosphate atoms, these bonds are called as high enrgy bonds. Later, when needed, other cells break down to use the energy inside the ATP which is produced by mitochondria.

i think it is true in my reasonment ..