The organelle that breaks down food into molecules the cell can use for energy is the mitochondrion.

Here's why:

* Mitochondria are often called the "powerhouses" of the cell. They are responsible for cellular respiration, a process that takes in nutrients (like glucose) and oxygen, and converts them into usable energy (ATP) for the cell to perform its functions.

* Lysosomes are also involved in breaking down materials, but their primary function is to digest waste products, cellular debris, and invading pathogens.

Let me know if you'd like to know more about mitochondria or cellular respiration!