Which organelle is the powerhouse of the cell?

• A. Nucleus
• B. Chloroplast
• C. Mitochondria
• D. Ribosome

Answer: (C)

The main idea here is energy production inside the cell. Mitochondria generate most of the cell’s ATP, the molecule cells use for energy, through cellular respiration. They take the products of nutrient breakdown and oxygen and drive the electron transport chain and ATP synthase to make ATP. Their inner membrane folds, called cristae, increase surface area to maximize this energy production. They even have their own circular DNA and a double membrane, reflecting their important role.

Other organelles have different jobs: the nucleus stores genetic material, and ribosomes build proteins. Chloroplasts, found in plants and some algae, capture light energy to make sugars via photosynthesis, which is how those cells store energy, but the immediate, portable energy for most cellular activities comes from mitochondria. That’s why these organelles are referred to as the powerhouse.