( Iron ( ( is ( essential ( for ( ( the formation ) ( of ( ( the hemoglobin ) ( within ( these cells ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Iron)) (VP (VBZ is) (ADJP (JJ essential) (PP (IN for) (NP (NP (DT the) (NN formation)) (PP (IN of) (NP (NP (DT the) (NN hemoglobin)) (PP (IN within) (NP (DT these) (NNS cells))))))))) (. .)))
Iron is essential for the formation of the hemoglobin within these cells.
(ROOT (S (NP (NNP Iron) (NNS ions)) (VP (VBP are) (ADJP (JJ critical) (PP (IN for) (NP (NP (DT the) (NN formation)) (PP (IN of) (NP (NN hemoglobin))))))) (. .)))