( ( In ( a ( human cell ) ) ) ( there ( ( are ( ( 23 pairs ) ( of chromosomes ) ) ) . ) ) )
(ROOT (S (PP (IN In) (NP (DT a) (JJ human) (NN cell))) (NP (EX there)) (VP (VBP are) (NP (NP (CD 23) (NNS pairs)) (PP (IN of) (NP (NNS chromosomes))))) (. .)))
In a human cell there are 23 pairs of chromosomes.
(ROOT (S (NP (NNS Humans)) (VP (VBP have) (NP (NP (CD 23) (JJ pairs) (NNS pairs)) (PP (IN of) (NP (NNS chromosomes))))) (. .)))