( ( That metabolism ) ( ( is ( ( ( the combination ) ( of ( all ( of ( the ( chemical reactions ) ) ) ) ) ) ( that ( take ( place ( in ( an organism ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT That) (NN metabolism)) (VP (VBZ is) (NP (NP (DT the) (NN combination)) (PP (IN of) (NP (NP (DT all)) (PP (IN of) (NP (DT the) (NN chemical) (NNS reactions))))) (SBAR (WHNP (WDT that)) (S (VP (VBP take) (NP (NP (NN place)) (PP (IN in) (NP (DT an) (NN organism))))))))) (. .)))
That metabolism is the combination of all of the chemical reactions that take place in an organism.
(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.