( ( ( The sum ) ( of ( ( all ( the ( biochemical reactions ) ) ) ( in ( an organism ) ) ) ) ) ( ( is ( called metabolism ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (PDT all) (DT the) (JJ biochemical) (NNS reactions)) (PP (IN in) (NP (DT an) (NN organism)))))) (VP (VBZ is) (VP (VBN called) (NP (NN metabolism)))) (. .)))
The sum of all the biochemical reactions in an  organism is called metabolism.
(ROOT (S (NP (JJ Biochemical) (NNS reactions)) (VP (VBP take) (NP (NP (NN place)) (PP (IN inside) (NP (NP (DT the) (NNS organisms) (POS ')) (NNS cells))))) (. .)))