Final answer:
The organelle responsible for breaking down food to release energy is the mitochondria, often called the "powerhouses" of the cell.
Step-by-step explanation:
The organelle where food is taken and broken down in the presence of oxygen to release energy is the mitochondria. Mitochondria are often called the "powerhouses" or "energy factories" of the cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule.
Inside the mitochondria, cellular respiration takes place, using oxygen and glucose to produce ATP and carbon dioxide as a waste product.
For example, active human muscle cells contain thousands of mitochondria to meet their high energy needs, while less active cells such as red blood cells do not have any.