What is the role of mitochondria?

• A. It stores genetic material.
• B. It regulates water balance.
• C. It synthesizes proteins.
• D. It releases energy from glucose during respiration (ATP production).

Answer: (D)

The main idea here is that mitochondria power the cell by producing ATP through respiration. They host the aerobic steps of cellular respiration—the Krebs cycle and the electron transport chain—where glucose is broken down and energy is captured as ATP, the cell’s usable energy. Oxygen is used in the process, and water (plus CO2) are byproducts. Because of this role, mitochondria are described as the cell’s powerhouses.

Other options aren’t their primary job: storing genetic material is mainly the job of the nucleus (though mitochondria do contain some DNA); regulating water balance is handled by other structures like membranes and vacuoles; and protein synthesis mainly happens on ribosomes, not in mitochondria.