( ( ( 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 (SBAR (WHADVP (WRB When)) (S (NP (NNS substances)) (VP (VBP pass) (PP (IN through) (NP (DT the) (NN cell) (NN membrane))) (PP (IN without) (S (VP (VBG needing) (NP (DT any) (NN energy)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (VP (VBN called) (NP (JJ passive) (NN transport)))) (. .)))