Question

Please complete the sentence:
Osmosis is the movement of ....across a .....due to .......

Answer 1

Osmosis is the movement of solvent molecules across a semi-permeable membrane due to concentration difference. 
[From High concentration of solvent, i.e dilute solution to low concentration of solvent, i.e concentrated solution.]

Answer 2

Osmosis is the movement of water molecules across a partially permeable membrane down  a water potential gradient .