Biology HL Internal Assessment
Cedar International School
Rate of Osmosis
If there is an increased concentration gradient of sucrose in the solution then will there be an increase rate of osmosis in the Potato?
Water potential is the measure of the propensity of water molecules to move from one place to another across a membrane. Water always moves from regions of high water potential to low water potential. Thus, osmosis is the passive diffusion of water through a partially permeable membrane driven by the difference in concentrations on the two sides of the membrane, aiming to create equilibrium with the solute concentration on both sides. The water flows in response to the difference in molarity of the membrane and moves through the membrane from high concentration of water (lower solute concentration), to a lower concentration of water (higher solute concentration). Thus, it is the passage of water molecules from a weaker solution into a stronger solution, ultimately, aiming to dilute the stronger concentration.
In essence, the one side of the membrane where there is a lower concentration of solute, more water molecules will begin to collide into the pores in the membrane. With more strikes into the membrane, more molecules have the advantage of passing through these pores, thus resulting in a net diffusion of water. This process requires a membrane in order to work and never moves by active transport.
In order to describe the differences in the solutions with the process of osmosis, three terms are used; isotonic, hypertonic, and hypotonic. Isotonic is used to refer to the solutions when they have equal concentration of solutes, hypertonic is used the refer to the solution with the higher concentration in solutes, and hypotonic refers to the solution with the lower concentration of solutes.
The movement of water across a membrane causes a pressure known as osmotic pressure. “If the pressure in the...