D2.3.9 Movement of water from higher to lower water potential (HL)

What drives the movement of water in biological systems?

Differences in potential energy.

What is the effect of positive pressure in a plant cell?

Positive pressure in a turgid plant cell increases water potential and can drive water out of the cell.

What is the effect of negative pressure in xylem vessels?

Negative pressure (tension) generated during transpiration lowers water potential and pulls water upward through the xylem.

List one process that relies on the movement of water from higher to lower potential.

Nutrient transport through the plant vascular system.

What is water potential?

Water potential is the potential energy of water in a system relative to pure water, determining the direction of water movement.

What happens to water potential when solutes are added?

The water potential becomes more negative due to decreased free energy of water molecules.

Why is maintaining water potential important for cells?

It maintains turgor pressure, regulates cellular water balance, and ensures proper physiological function.

What is turgor pressure?

Turgor pressure is the hydrostatic pressure exerted by the cell's contents against the cell wall.

How does water potential affect nutrient transport in plants?

Water movement from regions of higher to lower water potential enables the translocation of nutrients through plant tissues.

Can you give an example of a system where minimizing potential energy drives movement?

River systems, where water flows downhill to lower gravitational potential energy.

What is the relationship between water potential and solute concentration?

Increasing solute concentration lowers (makes more negative) the water potential.

How does water move across cell membranes?

Water moves across cell membranes by osmosis, driven by differences in water potential.

Why do water molecules move to achieve equilibrium?

They move to minimize potential energy differences, achieving thermodynamic equilibrium.

On the water potential scale, where does water flow?

Water flows from regions of higher (less negative) water potential to regions of lower (more negative) water potential.

How do solutes affect water potential?

Solutes reduce the free energy of water, thereby decreasing water potential.

Why does water move in the presence of solutes?

Water moves to equalize solute concentrations and reduce osmotic gradients.

What role do pressure differences play in water movement?

Pressure differences modify the pressure potential component of water potential, creating forces that either push or pull water.

What is the difference between osmotic potential and pressure potential?

Osmotic potential (solute potential) is the component of water potential due to solute concentration, always negative; pressure potential is the physical pressure acting on water, which can be positive or negative.