( ( As ( biological catalysts ) ) ( , ( enzymes ( ( reduce ( ( the amount ) ( of ( energy ( required ( for ( chemical reactions ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (JJ biological) (NNS catalysts))) (, ,) (NP (NNS enzymes)) (VP (VBP reduce) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (VP (VBN required) (PP (IN for) (NP (NN chemical) (NNS reactions)))))))) (. .)))
As biological catalysts, enzymes reduce the amount of energy required for chemical reactions.
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (VP (VBN required) (S (VP (TO to) (VP (VB begin) (NP (DT a) (JJ chemical) (NN reaction))))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT the) (NN activation) (NN energy))))) (. .)))