( ( Plant cells ) ( ( ( possess ( ( ( a ( cell wall ) ) , ) animals ) ) never ) . ) )
(ROOT (S (NP (NNP Plant) (NNS cells)) (VP (VBP possess) (NP (NP (DT a) (NN cell) (NN wall)) (, ,) (NP (NNS animals))) (ADVP (RB never))) (. .)))
Plant cells possess a cell wall, animals never.
(ROOT (S (NP (DT A) (NN cell) (NN wall)) (VP (VBZ is) (VP (VBN found) (PP (PP (IN in) (NP (DT a) (NN plant) (NN cell))) (CONJP (CC but) (RB not)) (PP (IN in) (NP (DT an) (NN animal) (NN cell)))))) (. .)))
A cell wall is found in a plant cell but not in an animal cell.