( ( A ( water molecule ) ) ( ( is ( ( made up ) ( of ( ( ( one ( oxygen atom ) ) and ) ( two ( hydrogen atoms ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN water) (NN molecule)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NP (CD one) (NN oxygen) (NN atom)) (CC and) (NP (CD two) (NN hydrogen) (NNS atoms)))))) (. .)))
A water molecule is made up of one oxygen atom and two hydrogen atoms.
(ROOT (S (NP (NP (CD 2) (NN hydrogen)) (, ,) (NP (CD 1) (NN oxygen) (NNS atoms))) (VP (VBP combine) (S (VP (TO to) (VP (VB make) (PRT (RP up)) (NP (NP (DT a) (NN molecule)) (PP (IN of) (NP (NN water)))))))) (. .)))
2 hydrogen, 1 oxygen atoms combine to make up a molecule of water.