( yeast ( ( are ( single-celled forms ) ) . ) )
(ROOT (S (NP (NN yeast)) (VP (VBP are) (NP (JJ single-celled) (NNS forms))) (. .)))
yeast are single-celled forms.
(ROOT (S (NP (NNP Single-celled)) (VP (VBP are) (ADJP (JJ yeasts))) (. .)))