( ( metabolism ( ( The sum ) ( of ( ( ( all ( chemical reactions ) ) ( -LRB- ( ( energy exchanges ) -RRB- ) ) ) ( in cells ) ) ) ) ) . )
(ROOT (NP (NP (NN metabolism)) (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (NP (DT all) (JJ chemical) (NNS reactions)) (PRN (-LRB- -LRB-) (NP (NN energy) (NNS exchanges)) (-RRB- -RRB-))) (PP (IN in) (NP (NNS cells)))))) (. .)))
metabolism The sum of all chemical reactions (energy exchanges) in cells.
(ROOT (S (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (DT all) (JJ chemical) (NNS reactions)) (SBAR (WHNP (WDT that)) (S (VP (VBP take) (NP (NN place)) (PP (IN within) (NP (DT an) (NN organism))))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (NN metabolism))))) (. .)))
The sum of all chemical reactions that take place within an organism is known as metabolism.