What are the tiny discs found in plant cells that contain chlorophyll?

Chloroplasts are the tiny discs found in plant cells that contain chlorophyll, the green pigment crucial for photosynthesis. This process allows plants to convert sunlight, carbon dioxide, and water into glucose and oxygen, providing energy for the plant and oxygen for other living organisms. Chloroplasts are essential for this conversion, as chlorophyll captures light energy. The unique structure of chloroplasts, which includes thylakoids organized into stacks (known as grana), is specifically adapted to maximize their efficiency in capturing light energy. This makes chloroplasts critical to the survival and growth of plants, as well as to the ecosystems that rely on them.

The other options do not serve this function: mitochondria are responsible for energy production through cellular respiration, the nucleus contains the cell's genetic material and controls its activities, and cell membranes protect the cell and regulate what enters and exits but do not participate in photosynthesis.