( ( ( A ( major role ) ) ( of ( the ( plasma membrane ) ) ) ) ( ( is ( ( transporting substances ) ( ( ( into and ) out ) ( of ( the cell ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (JJ major) (NN role)) (PP (IN of) (NP (DT the) (NN plasma) (NN membrane)))) (VP (VBZ is) (VP (VBG transporting) (NP (NNS substances)) (PP (IN into) (CC and) (IN out) (PP (IN of) (NP (DT the) (NN cell)))))) (. .)))
A major role of the plasma membrane is transporting substances into and out of the cell.
(ROOT (S (NP (NNP Passive) (NN transport)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NNS substances)) (VP (VBP cross) (NP (DT the) (NN plasma) (NN membrane)) (PP (IN without) (NP (NP (DT any) (NN input)) (PP (IN of) (NP (NN energy))))) (PP (IN from) (NP (DT the) (NN cell))))))) (. .)))