Lecture on Effects of Salt and Osmosis

Introduction

• Location and Childhood Experience:
  • West Texas winters: cold, minimal snow, icy roads.
  • Roads salted to prevent icing, lower freezing point.
  • Negative impact: roadside plants often die.

Salt and Plants

• Winter Impact:
  • Salt affects even hardy plants during winter.
• Hurricane Effect:
  • Coastal hurricanes dump salty ocean water into soil.
  • Long-term impact: kills plants and trees that survived the hurricane.
• Plants and Salt:
  • Osmosis is key to understanding plants' dislike for salt.

Understanding Osmosis

• Definition:
  • Movement of water through a semi-permeable membrane.
  • Water moves from high to low concentration areas.
  • Passive transport: no energy required.
• Solute and Solvent:
  • Solutes (salt, sugar) dissolve in solvent (water).
  • Water moves to areas with higher solute concentration.

Osmosis Demonstration: The U-tube

• Setup:
  • Semi-permeable membrane in the middle.
  • Equal water levels on both sides initially.
• Salt Added:
  • Adding salt to side B increases solute concentration.
  • Water moves to side B, equalizing concentrations.

Osmosis Vocabulary

• Hypertonic:
  • Higher solute concentration.
  • Side B is hypertonic to side A.
• Hypotonic:
  • Lower solute concentration.
  • Side A is hypotonic compared to side B.

Real-Life Applications of Osmosis

• IV Fluids in Hospitals:
  • IV fluids are not pure water to avoid cell damage.
  • Isotonic solutions prevent red blood cell swelling or bursting.
• Aquarium Fish:
  • Saltwater fish cannot survive in freshwater due to osmosis.

Adaptations in Fish

• Special Adaptations:
  • Some fish, like salmon, adapt to both environments.
• Osmosis in Plants:
  • Plant root cells absorb water from soil via osmosis.
  • Root hair cells are hypertonic to saturated soil.

Pressure Potential in Plants

• Water Potential Formula:
  • Water potential = pressure potential + solute potential.
  • Adding solute lowers solute potential.
  • Pressure raises pressure potential.
• Potato Core Lab Example:
  • Distilled water causes potato cells to gain water.
  • Turgor pressure from water entry is critical for plant structure.

Conclusion

• Importance of Osmosis:
  • Essential for movement of water, a valuable resource.
• Final Note:
  • Curiosity encouraged.