( They ( also ( ( ( play ( a ( crucial role ) ) ) ( as ( ( a ( ( check and ) balance ) ) ( on ( ( the powers ) ( of ( ( Congress and ) ( the ( Supreme Court ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (PRP They)) (ADVP (RB also)) (VP (VBP play) (NP (DT a) (JJ crucial) (NN role)) (PP (IN as) (NP (NP (DT a) (NN check) (CC and) (NN balance)) (PP (IN on) (NP (NP (DT the) (NNS powers)) (PP (IN of) (NP (NP (NNP Congress)) (CC and) (NP (DT the) (NNP Supreme) (NNP Court))))))))) (. .)))
They also play a crucial role as  a check and balance on the powers of Congress and the Supreme Court.
(ROOT (S (NP (NNP Beneficial) (NNS fungi)) (VP (VBP play) (NP (NP (DT a) (JJ crucial) (NN role)) (PP (IN in) (NP (NP (NN balance)) (PP (IN of) (NP (NNS ecosystems))))))) (. .)))
Beneficial fungi play a crucial role in balance of ecosystems.