( Diffusion ( ( is ( ( the process ) ( ( by which ) ( ions ( move ( from ( ( an area ) ( of ( higher ( to ( lower concentration ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Diffusion)) (VP (VBZ is) (NP (NP (DT the) (NN process)) (SBAR (WHPP (IN by) (WHNP (WDT which))) (S (NP (NNS ions)) (VP (VBP move) (PP (IN from) (NP (NP (DT an) (NN area)) (PP (IN of) (NP (NP (JJR higher)) (PP (TO to) (NP (JJR lower) (NN concentration)))))))))))) (. .)))
Diffusion is the process by which ions move from an area of higher to lower concentration.
(ROOT (S (NP (NNP Diffusion)) (VP (VBZ is) (NP (NP (DT the) (NN process)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (DT a) (NN substance)) (ADVP (RB naturally)) (VP (VBZ moves) (PP (IN from) (NP (NP (DT an) (NN area)) (PP (IN of) (NP (NP (JJR higher)) (PP (TO to) (NP (JJR lower) (NN concentration)))))))))))) (. .)))
Diffusion is the process in which a substance naturally moves from an area of higher to lower concentration.