( ( If ( you ( want ( a ( ( more technical ) term ) ) ) ) ) ( , ( it ( ( would ( be ( ( ( osmosis and ) osmotic ) ( pressure differences ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN If) (S (NP (PRP you)) (VP (VBP want) (NP (DT a) (ADJP (RBR more) (JJ technical)) (NN term))))) (, ,) (NP (PRP it)) (VP (MD would) (VP (VB be) (NP (ADJP (JJ osmosis) (CC and) (JJ osmotic)) (NN pressure) (NNS differences)))) (. .)))
If you want a more technical term, it would be osmosis and osmotic pressure differences.
(ROOT (S (S (VP (VBG Applying) (NP (DT a) (NN pressure) (JJR greater)) (PP (IN than) (NP (NP (DT the) (JJ osmotic) (NN pressure)) (PP (IN of) (NP (DT a) (NN solution))))))) (VP (MD will) (VP (VB cause) (NP (JJ reverse) (NNS osmosis)))) (. .)))