IGCSE Biology glossary
Net movement
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
The overall direction in which particles move when diffusion or osmosis occurs. Individual molecules move randomly in all directions, but there is a net movement from the region of higher concentration to the region of lower concentration because more molecules move in that direction.
What to include in an exam answer
Including 'net movement' in definitions of diffusion and osmosis is required for full marks. It acknowledges that molecules move in both directions but overall movement is in one direction.
Example in context
Explain why there is a net movement of oxygen into a respiring cell (2 marks): The concentration of oxygen is higher outside the cell than inside (where it is used up in respiration), so there is a net movement of oxygen molecules into the cell down the concentration gradient by diffusion.
Related syllabus topic
Movement into & out of cells