( It ( ( ( does not ) ( ( require ( activation energy ) ) ( to begin ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ does) (RB not) (VP (VB require) (NP (NN activation) (NN energy)) (S (VP (TO to) (VP (VB begin)))))) (. .)))
It does not require activation energy to begin.
(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))))) (. .)))