Final answer:
Osmosis is the movement of water through a semipermeable membrane from an area of high to low water concentration, while dialysis is the separation of small solutes and ions from larger particles through a membrane with larger pores. Both are critical for kidney functions in blood cleansing but differ in particle size selectivity.
Step-by-step explanation:
Osmosis and dialysis are both processes that involve the movement of particles across a semipermeable membrane, but they differ in the types of particles they transport. Osmosis is specifically the transport of water molecules through a semipermeable membrane from a region of high water concentration to a region of low water concentration. This process is driven by the imbalance in water concentration, such as when soaking a swollen ankle in Epsom salt, where the water moves from the body into the salt to achieve balance. In contrast, dialysis involves the transport of various small molecules and ions through a semipermeable membrane due to concentration differences, separating them from larger particles such as proteins and starch, which are too large to pass through the pores of the membrane.
Another key difference between osmosis and dialysis is the size of the pores in the semipermeable membrane. Osmosis typically deals with smaller pores that only allow the passage of water, while dialysis uses membranes with larger pores that permit both solvents and small solute molecules to pass, leaving behind larger molecules such as colloids and proteins. Both processes are essential for biological functions, particularly in the kidneys, which use these mechanisms to cleanse the blood.