What is the primary function of chloroplasts in plant cells?

The primary function of chloroplasts in plant cells is photosynthesis. Chloroplasts are specialized organelles that contain chlorophyll, the green pigment that captures light energy from the sun. This light energy is converted into chemical energy through the process of photosynthesis, where carbon dioxide from the atmosphere and water from the soil are transformed into glucose (a sugar that serves as food for the plant) and oxygen, which is released as a byproduct.

During photosynthesis, the captured solar energy is harnessed in the thylakoid membranes within the chloroplasts, where it facilitates the light-dependent reactions. These reactions convert light energy into ATP and NADPH, which are energy-rich molecules. Subsequently, in the stroma of the chloroplast, the light-independent reactions (Calvin cycle) utilize ATP and NADPH to synthesize glucose from carbon dioxide.

While other organelles perform functions like energy production through respiration, water storage, and protein synthesis, none of these processes define the role of chloroplasts. Their unique structure and presence of chlorophyll specifically support the essential process of photosynthesis, making it the correct answer.