Which organelle is responsible for producing energy in cells through cellular respiration?

• A. The nucleus
• B. The ribosome
• C. The mitochondrion
• D. The chloroplast

Answer: (C)

Energy production through cellular respiration happens in the mitochondria. These organelles take the chemical energy stored in glucose and, with the help of oxygen, convert it into ATP, the molecule cells use for work. The mitochondria carry out the steps after glycolysis: the pyruvate is processed, carbon dioxide is released in the citric acid cycle, and the electron transport chain uses the energy from electrons to build a large amount of ATP with ATP synthase. That’s why mitochondria are called the cell’s energy producers. The nucleus stores genetic material, ribosomes synthesize proteins, and chloroplasts (in plants) carry out photosynthesis to make sugars from light—not the immediate energy output of respiration in most cells.