( ( Passive transport ) ( ( involves ( ( the movement ) ( of ( molecules ( across ( ( the cell ) ( ( membrane ( without ( ( an input ) ( of energy ) ) ) ) ( by ( the cell ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Passive) (NN transport)) (VP (VBZ involves) (NP (NP (DT the) (NN movement)) (PP (IN of) (NP (NP (NNS molecules)) (PP (IN across) (NP (NP (DT the) (NN cell)) (VP (VBN membrane) (PP (IN without) (NP (NP (DT an) (NN input)) (PP (IN of) (NP (NN energy))))) (PP (IN by) (NP (DT the) (NN cell)))))))))) (. .)))
Passive transport involves the movement of molecules across the cell membrane without an input of energy by 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)))) (. .)))