( ( 8.2 ( -8.3 ( Cell Division ) ) ) ( ( ( ( is ( at ( ( the heart ) ( of ( ( the reproduction ) ( of ( ( cells and ) organisms ) ) ) ) ) ) ) , ) ( because ( cells ( ( come only ) ( from ( preexisting cells ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP 8.2) (NNP -8.3) (NNP Cell) (NNP Division)) (VP (VBZ is) (PP (IN at) (NP (NP (DT the) (NN heart)) (PP (IN of) (NP (NP (DT the) (NN reproduction)) (PP (IN of) (NP (NNS cells) (CC and) (NNS organisms))))))) (, ,) (SBAR (IN because) (S (NP (NNS cells)) (VP (VBP come) (ADVP (RB only)) (PP (IN from) (NP (VBG preexisting) (NNS cells))))))) (. .)))
8.2 -8.3 Cell Division is at the heart of the reproduction of cells and organisms, because cells come only from preexisting cells.
(ROOT (S (NP (NNS Cells)) (VP (VBP come) (PP (IN from) (NP (VBG preexisting) (NNS cells)))) (. .)))