( Diffusion ( ( is ( ( a ( molecular process ) ) ( of ( substances ( ( moving ( from ( areas ( of ( ( relatively high ) concentrations ) ) ) ) ) ( to ( areas ( of ( ( relatively low ) concentrations ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Diffusion)) (VP (VBZ is) (NP (NP (DT a) (JJ molecular) (NN process)) (PP (IN of) (NP (NP (NNS substances)) (VP (VBG moving) (PP (IN from) (NP (NP (NNS areas)) (PP (IN of) (NP (ADJP (RB relatively) (JJ high)) (NNS concentrations))))) (PP (TO to) (NP (NP (NNS areas)) (PP (IN of) (NP (ADJP (RB relatively) (JJ low)) (NNS concentrations)))))))))) (. .)))
Diffusion is a molecular process of substances moving from areas of relatively  high concentrations to areas of relatively low concentrations.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT the) (NN movement)) (PP (IN of) (NP (DT a) (NN substance)))) (PP (IN from) (NP (NP (DT an) (NN area)) (PP (IN of) (NP (NP (DT a) (JJR higher) (NN amount)) (PP (IN toward) (NP (NP (DT an) (NN area)) (PP (IN of) (NP (JJR lower) (NN amount) (NN diffusion)))))))))) (. .)))