D2.3 Water Potential

Solvation

Combination of a solvent and a solute

The positive charged ions are attracted to

Partially negative oxygen poles

The negative charged ions are attracted to

Partial + hydrogen poles

As water molecules change position, hydrogen bonds are __________

Broken & formed repeatedly

Osmosis

The net movement of water from a low concentration to a high concentration through a semi-permeable membrane

3 terms for describing osmosis

• Hypotonic

• Hypertonic

• Isotonic

Hypotonic

Lower concentration → cell swells

Hypertonic

Higher concentration → cell shrinks

Isotonic

Same concentration → cell stays the same

Equal concentration levels

Dynamic equilibrium

Plasma membranes are _____

Semi-permeable

Turgid cells

Cells that have become pressurised, swollen

Flaccid

Floppy (in plants)

Wilting

When leaves/stems bend downwards

Plasmolysis

Plasma membrane detaches from cell wall

Units for water potential

• Kilopascals (kPa)

• Megapascals (MPa)

Factors influencing water potential

• Hydrostatic pressure

• Solute concentration

How does solid granule of NaCl become a solute when in water

• Hydrogen bonds with Na⁺ and Cl⁻

• Water surrounds them to prevent the ionic bonds from reforming

Compare & Contrast how animals and plants are affected by hypotonic solutions

	Plants Cells	Animal Cells
Similarities	Both will swell	Both will swell
Differences	Becomes turgid	Becomes lyse

Compare & Contrast how animals and plants are affected by hypertonic solutions

	Plant Cells	Animal Cells
Similarities	Both may die	Both may die
Differences	Becomes flaccid	Becomes shrivel