( ( Passive transport ) ( ( occurs ( when ( substances ( ( ( cross ( the ( plasma membrane ) ) ) ( without ( ( any input ) ( of energy ) ) ) ) ( from ( 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))))))) (. .)))
Passive transport occurs when substances cross the plasma membrane without any input of energy from the cell.
(ROOT (S (NP (DT The) (NN term) (JJ passive) (NN transport)) (VP (VBZ describes) (NP (DT a) (NN way)) (SBAR (IN that) (S (NP (JJ small) (NNS molecules) (CC or) (NNS ions)) (VP (VBP move) (PP (IN across) (NP (NP (DT the) (NN cell)) (VP (VBN membrane) (PP (IN without) (NP (NP (NN input)) (PP (IN of) (NP (NN energy))))) (PP (IN by) (NP (DT the) (NN cell)))))))))) (. .)))