Investigating Osmosis: Practical Application

To investigate osmosis, scientists often use experiments involving plant tissues, such as potato slices, in various concentrations of salt solutions.

The graph presented shows the percentage change in mass of potato tissue when placed in solutions of different concentrations:

• The x-axis represents the salt solution concentration in mol/dm³
• The y-axis shows the percentage change in mass of the potato tissue

Key observations from the graph:

1. At lower salt concentrations (hypotonic solutions), the potato gains mass due to water uptake.
2. At higher salt concentrations (hypertonic solutions), the potato loses mass as water leaves the cells.
3. The isotonic point (Q) is where there is no change in mass, indicating equal water potentials inside and outside the potato cells.

Example: At the isotonic point (Q), there is no net movement of water because the water potential inside the potato and in the solution is the same.

Highlight: Understanding osmosis through such experiments is crucial for comprehending cellular processes and developing applications in fields like medicine and agriculture.

This investigation demonstrates the practical application of osmosis principles and provides a visual representation of how cells respond to different osmotic conditions.

Osmosis and Its Effects on Cells

Osmosis is a specific type of diffusion involving the movement of water molecules across a selectively permeable membrane.

Definition: Osmosis is the net movement of water molecules from an area of high water potential to an area of low water potential, down a water potential gradient, occurring passively without energy input.

Key concepts related to osmosis include:

• Water potential: The concentration of water in a solution
• Hypertonic solution: High solute concentration and low water potential
• Hypotonic solution: Low solute concentration and high water potential
• Isotonic solution: Equal water potential and solute concentration on both sides of the membrane

The osmosis effect on plant and animal cells varies depending on the tonicity of the surrounding solution:

1. In a hypotonic solution:

   • Animal cells may undergo lysis (burst)
   • Plant cells become turgid but are protected from bursting by their cell wall

2. In a hypertonic solution:

   • Animal cells become crenated (shriveled)
   • Plant cells undergo plasmolysis (cell membrane pulls away from cell wall)

3. In an isotonic solution:

   • Animal cells remain normal
   • Plant cells become flaccid (water moves in and out at equal rates)

Vocabulary:

• Plasmolysis: When a plant cell shrinks in a hypertonic solution
• Crenation: The shriveling of an animal cell in a hypertonic solution
• Lysis: The bursting of an animal cell in a hypotonic solution
• Turgid: A plant cell's state when fully inflated with water in a hypotonic solution