( ( The ( cell membrane ) ) ( ( is ( ( a ( ( selectively permeable ) barrier ) ) ( that ( allows ( ( some substances ) ( to ( ( ( pass through ) ( to ( ( the inside ) ( of ( the cell ) ) ) ) ) ( while ( ( keeping others ) out ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN cell) (NN membrane)) (VP (VBZ is) (NP (NP (DT a) (ADJP (ADVP (RB selectively)) (JJ permeable)) (NN barrier)) (SBAR (WHNP (WDT that)) (S (VP (VBZ allows) (S (NP (DT some) (NNS substances)) (VP (TO to) (VP (VB pass) (PRT (RP through)) (PP (TO to) (NP (NP (DT the) (NN inside)) (PP (IN of) (NP (DT the) (NN cell))))) (SBAR (IN while) (S (VP (VBG keeping) (NP (NNS others)) (PRT (RP out))))))))))))) (. .)))
The cell membrane is a selectively permeable barrier that allows some substances to pass through to the inside of the cell while keeping others out.
(ROOT (S (NP (NP (DT A) (NN cell) (POS 's)) (NN membrane)) (VP (VBZ provides) (NP (DT a) (NN barrier) (S (VP (TO to) (VP (VB keep) (NP (NN extracellular) (NNS materials)) (PP (IN from) (S (VP (VBG mixing) (PP (IN with) (NP (PRP$ its) (JJ internal) (NNS components))))))))))) (. .)))