Final answer:
Counter current flow of blood and dialysate increases the rate of solute exchange during dialysis.
Step-by-step explanation:
The counter current flow of blood and dialysate in the kidneys increases the rate of solute exchange during the process of dialysis. The presence of a concentration gradient between the blood and the dialysate allows for the efficient removal of waste products, such as urea, from the blood. As the blood flows in one direction and the dialysate flows in the opposite direction, it creates an osmotic pressure that enhances the diffusion of solutes across the semipermeable membrane.