Take a look at the more detailed diagram of photosynthesis above. Photosynthesis occurs in two phases. The first phase of photosynthesis is known as the light-dependent reactions. The light reactions occur in the thylakoid. Here, sunlight and water are used to create chemical energy (ATP and NADPH) for the second phase of photosynthesis, while oxygen is released as a product. The next phase of photosynthesis, the Calvin Cycle, occurs in the gel-like material called the stroma. In the Calvin cycle, the chemical energy from the light-dependent reactions is used to help convert carbon dioxide into the main product of photosynthesis, glucose sugar, or food for the plant cells. 8. Explain the first phase of photosynthesis, the light-dependent reaction (Where does it occur? What happens?) 9. Explain the second phase of photosynthesis, the Calvin Cycle (Where does it occur? What happens?) Light NADP Stroma Thylakoids ADP Light. Reactions Calvin Cycle NADPH Chloroplast Sugar