Which organelle is the site of photosynthesis in plant cells?

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

Answer: (D)

Photosynthesis happens in chloroplasts, the specialized compartments in plant cells that capture light energy. These organelles contain chlorophyll, the pigment that absorbs light, and the thylakoid membranes where the light-dependent reactions occur. During these reactions, light energy is used to split water, releasing oxygen and producing ATP and NADPH, which then power the Calvin cycle to build sugars from CO2. In contrast, mitochondria are where energy is released from sugars through cellular respiration, the nucleus stores and manages genetic information, and ribosomes build proteins. Because chloroplasts are the structures equipped to capture light and convert it into chemical energy, they are the site of photosynthesis in plant cells.