Osmosis and Water Potential- Amoeba sisters

Plants, even hardy species, suffer from salt exposure, with long-term effects from saltwater flooding leading to mortality.

Osmosis: Movement of water through a semi-permeable membrane (like cell membranes).
Water molecules can move freely through cell membranes or via protein channels (aquaporins).
Passive Transport: Water movement does not require energy; it flows from a high concentration of water molecules to a low concentration.
A higher concentration of water typically indicates a lower concentration of solutes, driving water to regions with higher solute concentrations.

Visualizing osmosis with a U-tube with a semi-permeable membrane:
- Initially filled with equal water levels.
- Upon adding salt to one side (B), water moves to the side with higher solute concentration (B).
- The concept of equilibrium is when the movement of water molecules ceases to net change, even if molecules continue to move.

Side B is described as hypertonic (higher solute concentration), while Side A is hypotonic (lower solute concentration).
Water moves toward the hypertonic side (B), attempting to equalize solute concentrations.

In medical situations, IV fluids are not pure water, as pure water would lead to osmosis-related issues.
If pure water enters the bloodstream, red blood cells would swell due to the higher solute concentration inside them, potentially causing them to burst.
Safe IV fluids are isotonic, matching the solute concentration of blood plasma to prevent cell swelling or shrinking.

Saltwater fish cannot survive in freshwater due to osmotic pressure: freshwater has a lower solute concentration.
The cells of saltwater fish are hypertonic compared to freshwater, leading to water intake and potential death if exposed to freshwater.
Adaptations: Some fish, like salmon, can switch between fresh and saltwater environments due to special adaptations.

Plants absorb water through roots where root hair cells have a higher solute concentration than surrounding saturated soil.
Water moves into root hair cells, which are hypertonic in comparison to the hypotonic soil, leading to hydration.

Plant cells possess cell walls that prevent bursting from internal water pressure.
Pressure Potential: Involves calculating water potential by considering solute potential and pressure potential to understand water movement in cells.

Water potential = pressure potential + solute potential.
- More solutes correlate with lower solute potential.
- Pressure inside plant cells raises total water potential, ensuring turgor pressure.

Turgor pressure is vital for maintaining plant structure and preventing wilting, supporting upright growth.

Osmosis is fundamental for the movement of water in living organisms, crucial for hydration and proper cellular function.
The importance of understanding osmosis extends beyond plants to animals and ecosystems, emphasizing water's value.