( Cells ( also ( ( ( act ( as ( ( selective filters ) ( in ( ( the transport ) ( of ( ( ions and ) ( other molecules ) ) ) ) ) ) ) ) ( across ( their ( plasma membranes ) ) ) ) . ) ) )
(ROOT (S (NP (NNS Cells)) (ADVP (RB also)) (VP (VBP act) (PP (IN as) (NP (NP (JJ selective) (NNS filters)) (PP (IN in) (NP (NP (DT the) (NN transport)) (PP (IN of) (NP (NP (NNS ions)) (CC and) (NP (JJ other) (NNS molecules)))))))) (PP (IN across) (NP (PRP$ their) (NN plasma) (NNS membranes)))) (. .)))
Cells also act as selective filters in the transport of ions and other molecules across their plasma 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)))))))))) (. .)))