Question: where does the light reaction of photosynthesis occur?
Answer: on the thylakoid membranes

In photosynthesis , the light - dependent reactions take place on the thylakoid membranes . The inside of the thylakoid membrane is called the lumen , and outside the thylakoid membrane is the stroma , where the light - independent reactions take place . The thylakoid membrane contains some integral membrane protein complexes that catalyze the light reactions . There are four major protein complexes in the thylakoid membrane : Photosystem II ( PSII ) , Cytochrome b6f complex , Photosystem I ( PSI ) , and ATP synthase . These four complexes work together to ultimately create the products ATP and NADPH .