What role do chloroplasts play in plant cells?

• A. They store water inside the cell.
• B. They produce energy for the cell by cellular respiration.
• C. They help protect the cell from damage.
• D. They capture light energy to perform photosynthesis, producing glucose and oxygen.

Answer: (D)

Chloroplasts capture light energy to drive photosynthesis in plant cells. They use light energy, with the help of chlorophyll, to convert carbon dioxide and water into glucose, a sugar that stores chemical energy, and oxygen is released as a byproduct. This glucose can be used right away for energy or stored for later. This function is different from storing water (the vacuole’s job) and from producing energy through cellular respiration (a task of mitochondria). They also aren’t primarily for protection. So the process described—capturing light energy to perform photosynthesis and produce glucose and oxygen—best explains what chloroplasts do.