( ( referring ( to ( a cell ) ) ) ( that ( ( is ( firm ( due ( to ( water uptake ) ) ) ) ) . ) ) )
(ROOT (S (S (VP (VBG referring) (PP (TO to) (NP (DT a) (NN cell))))) (NP (DT that)) (VP (VBZ is) (ADJP (NN firm) (JJ due) (PP (TO to) (NP (NN water) (NN uptake))))) (. .)))
referring to a cell that is firm due to water uptake.
(ROOT (S (NP (RBS Most) (JJ growing) (NN plant) (NNS cells)) (VP (VBP expand) (PP (IN through) (NP (NN water) (NN uptake)))) (. .)))