( ( ( ( ( ( The ( first part ) ) ( of ( the ( photosynthetic process ) ) ) ) , ) ( often ( called ( the ( light ( reaction ( or ( light-dependant reaction ) ) ) ) ) ) ) ) , ) ( ( takes ( place ( in ( the thylakoids ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ first) (NN part)) (PP (IN of) (NP (DT the) (JJ photosynthetic) (NN process))) (, ,) (VP (ADVP (RB often)) (VBN called) (NP (DT the) (JJ light) (NN reaction) (CC or) (NN light-dependant) (NN reaction))) (, ,)) (VP (VBZ takes) (NP (NP (NN place)) (PP (IN in) (NP (DT the) (NNS thylakoids))))) (. .)))
The first part of the photosynthetic process, often called  the light reaction or light-dependant reaction, takes place in the  thylakoids.
(ROOT (S (NP (DT The) (JJ light) (NNS reactions)) (VP (VBP take) (NP (NP (NN place)) (PP (IN in) (NP (DT the) (NN thylakoid))))) (. .)))