Which organelle is found in plant and algae cells and is the site of photosynthesis?

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

Answer: (A)

Chloroplasts are the organelles responsible for photosynthesis in plant and algae cells. They contain chlorophyll, the pigment that captures light energy. This energy drives the transformation of carbon dioxide and water into glucose, with oxygen released as a byproduct. Chloroplasts have a double membrane and internal compartments—the thylakoid membranes where light-dependent reactions happen and the stroma where the Calvin cycle occurs—and they contain their own DNA. All of this explains why chloroplasts are found in plant and algae cells and serve as the site of photosynthesis. The other options don’t perform photosynthesis: mitochondria generate ATP through respiration, vacuoles store water and other substances, and ribosomes build proteins.