( ( Ion transport ) ( across ( cell membranes ) ) )
(ROOT (S (VP (VB Ion) (NP (NN transport)) (PP (IN across) (NP (NN cell) (NNS membranes))))))
Ion transport across cell membranes
(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)))))))))) (. .)))