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Osmosis is the process by which water molecules move across a semipermeable membrane from an area of lower solute concentration (hypotonic solution) to an area of higher solute concentration (hypertonic solution). This movement continues until there is an equal concentration of solutes on both sides of the membrane, reaching equilibrium. Recall that a solution is made of two things - a solute (salt, sugar, proteins, etc.) and a solvent (usually water).
Key Characteristics of Osmosis:
Semipermeable Membrane: Osmosis occurs through a semipermeable membrane that allows only certain molecules (like water) to pass while blocking others (like certain solutes).
Passive Process: It does not require energy (ATP) because it relies on the movement of water molecules using kinetic energy.
Concentration Gradient: Water moves from a hypotonic solution (low solute concentration) to a hypertonic solution (high solute concentration).
Factors Affecting Osmosis:
Temperature: Higher temperatures increase the kinetic energy of water molecules, speeding up the process.
Solute Concentration: As the difference in solute concentration on either side of the membrane increases, the rate of osmosis will also increase.
Solution Types (Highly Important):
1. Hypertonic solution - will have a higher solute concentration than the hypotonic solution.
- When cells are placed in a hypertonic solution, water leaves the cell causing it to shrink.
2. Hypotonic solution - will have a lower solute concentration than the hypertonic solution.
- When cells are place in a hypotonic solution, water floods the cell, and it may burst.
3. Isotonic solution - exist when both solutions have equal solute concentrations.
- When cells are in this solution, water will enter and leave the cell at the same rate, the cell will not change in size or volume.
Absorption of water by plant roots.
Movement of water in and out of red blood cells.
Regulation of fluid balance in cells and tissues.
Key Concept - if possible, water will always move toward the hypertonic solution.
Follow along with the simulation projected on BB, along with the reading above, to help answer 9-15.