Answer:
diffusion through a selectively permeable membrane
Step-by-step explanation:
The cell membrane selectively allows certain substances to enter or leave a cell . This implies that cell membranes are selectively permeable; they allow some substances to pass through, but not others.
Direct transport of materials across the cell membrane is often passive. Passive transport does not require energy to occur. Passive transport is the movement of substances from a region of higher concentration to a region of lower concentration. A concentration gradient is always required.
The diffusion through a selectively permeable membrane is an example of passive transport.
The iodine moves into the dialysis tube across the semi permeable cell membrane from a region of higher concentration to a region of lower concentration in response to a concentration gradient.