( ( These channels ) ( ( can ( be ( ( ( ( ( ( permanently open ) ( -LRB- ( ( free ( passive transport ) ) -RRB- ) ) ) , ) or ) ( open ( ( only when ) ( ( certain conditions ) ( are ( present ( in ( the ( cell membrane ) ) ) ) ) ) ) ) ) ( -LRB- ( ( gated ( passive transport ) ) -RRB- ) ) ) ) ) . ) )
(ROOT (S (NP (DT These) (NNS channels)) (VP (MD can) (VP (VB be) (ADJP (ADJP (RB permanently) (JJ open)) (PRN (-LRB- -LRB-) (S (VP (VB free) (NP (JJ passive) (NN transport)))) (-RRB- -RRB-)) (, ,) (CC or) (ADJP (JJ open) (SBAR (WHADVP (RB only) (WRB when)) (S (NP (JJ certain) (NNS conditions)) (VP (VBP are) (ADJP (JJ present) (PP (IN in) (NP (DT the) (NN cell) (NN membrane)))))))) (PRN (-LRB- -LRB-) (VP (VBN gated) (NP (JJ passive) (NN transport))) (-RRB- -RRB-))))) (. .)))
These channels can be permanently open ( free passive transport ), or open only when certain conditions are present in the cell membrane ( gated passive transport ).
(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)))) (. .)))