Which organelle contains its own DNA and is the powerhouse of the cell?

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

Answer: (D)

Mitochondria are the energy factories of the cell, producing most of the ATP the cell needs through cellular respiration. They contain their own circular DNA and ribosomes, which reflects their origin as independent organisms that joined the cell long ago. This organelle uses oxygen and glucose to generate ATP, along with byproducts like carbon dioxide and water, powering nearly all cellular activities. The nucleus holds the cell’s DNA and directs many functions, but it doesn’t generate significant energy itself. Chloroplasts also have their own DNA and capture energy by photosynthesis, but they’re present mainly in plant and some algal cells, not in all cells, so they aren’t the general powerhouse. That combination of energy production and own DNA identifies the mitochondrion as the correct choice.