Here's why:

* Mitochondria are often called the "powerhouses" of the cell.

* They are responsible for cellular respiration, a process that uses sugar (glucose) and oxygen to generate ATP (adenosine triphosphate), the primary energy currency of cells.

* This process involves several steps:

* Glycolysis: Glucose is broken down into pyruvate in the cytoplasm.

* Krebs Cycle (Citric Acid Cycle): Pyruvate is further broken down in the mitochondria, releasing electrons.

* Electron Transport Chain: The electrons from the Krebs cycle are used to create a proton gradient across the mitochondrial membrane. This gradient is then used to produce ATP.

So, while other organelles like lysosomes break down substances within the cell, it's the mitochondria that are specifically responsible for the breakdown of sugar to generate energy.