Which organelle is known as the powerhouse of the cell, generating ATP through cellular respiration?

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

Answer: (A)

The main idea here is identifying which cell organelle is responsible for producing most of the cell’s energy through cellular respiration. The mitochondrion is the powerhouse because it hosts the enzymes of the citric acid cycle and the electron transport chain, with ATP synthase generating ATP as electrons flow and a proton gradient is driven across the inner membrane. Energy extraction begins with glycolysis in the cytosol, then pyruvate enters the mitochondrion to feed the citric acid cycle and the electron transport chain, where the bulk of ATP is produced during oxidative phosphorylation. The inner membrane folds, called cristae, increase surface area to maximize ATP output. In contrast, the nucleus stores DNA, chloroplasts perform photosynthesis in plants to make glucose, and lysosomes break down waste materials; these organelles aren’t the main sites of ATP production via cellular respiration.