The two stages of photosynthesis are the light‑dependent reactions and the light‑independent reactions (Calvin cycle) , and they occur in different parts of the chloroplast: the light‑dependent reactions in the thylakoid membranes (grana) and the Calvin cycle in the stroma.

Light‑dependent reactions

  • These reactions need light directly and are the first stage of photosynthesis.
  • They occur in the thylakoid membranes of the chloroplast (the stacked discs called grana), where chlorophyll absorbs light to split water, release oxygen, and produce ATP and NADPH as energy‑rich molecules.

Light‑independent reactions (Calvin cycle)

  • These reactions do not require light directly, but they use the ATP and NADPH made in the light‑dependent reactions to drive sugar formation.
  • They occur in the stroma of the chloroplast, the fluid‑filled region surrounding the thylakoids, where carbon dioxide is fixed into organic molecules such as glucose.

Mini summary (TL;DR)

  • Stage 1: Light‑dependent reactions – in thylakoid membranes; make ATP, NADPH, and oxygen.
  • Stage 2: Calvin cycle (light‑independent) – in stroma; uses ATP and NADPH to make sugars from carbon dioxide.

Information gathered from public forums or data available on the internet and portrayed here.