Water Potential in Plants

What is the role of solute potential (Ψs) in water potential (Ψw)?

What is the typical range of pressure potential (Ψp) in plant cells during nighttime?

Which statement about pure water's water potential (Ψw) is accurate?

How does water typically move in relation to water potential?

Which of the following statements about osmosis is correct?

What primarily drives the movement of water in plants?

The water potential of pure water in an open container is defined as what value?

Which component of water potential considers the presence of solutes dissolving in water?

What is the formula for calculating water potential in a plant cell?

Which of the following factors is usually disregarded in osmosis for plant cells?

What happens to water potential when the concentration of solid particles increases in a solution?

In the context of thermodynamics, what is free energy a measure of?

Which factor increases water potential in a plant cell?

Water Potential in Plants

Water potential (Ψw) is a measure of the free energy of water, a modern term coined by Slatyer and Taylor (1960).
It explains water movement in plants more accurately than basing it on concentration differences.
Water moves from higher to lower water potential.
Pure water at standard pressure and temperature has a water potential of 0, the highest possible value.
Solution's water potential is always negative because solutes lower water's free energy.

Components of Water Potential

Water potential in plant cells is a sum of three factors:
- Matrix potential (Ψm): Water binding to cell walls and cytoplasm. Usually disregarded.
- Solute potential (Ψs): The decrease in water potential due to solutes. Always negative.
- Pressure potential (Ψp): Hydrostatic pressure within the cell. Usually positive, acting as turgor pressure.
The overall water potential equation is: Ψw = Ψs + Ψp + Ψm. In plant cells, Ψm is often negligible so the equation simplifies to Ψw = Ψs + Ψp.

Solute Potential (Ψs)

Solute potential (Ψs): The decrease in water potential due to dissolved solutes.
Always negative and expressed in bars.

Pressure Potential (Ψp)

Pressure potential (Ψp): The effect of hydrostatic pressure on water potential.
Usually positive (+5 to +15 bars). This pressure is a result of the cell wall pressure and turgor pressure.

Important Aspects of Water Potential (Ψw)

Pure water has the maximum (zero) water potential.
Water moves from higher to lower water potential.
Solutions always have a lower water potential than pure water.
Osmosis is the movement of water across a semi-permeable membrane driven by a difference in water potential.

Explore the concept of water potential in plants, including its definition and components. This quiz covers key terms like solute potential, pressure potential, and matrix potential. Understand how these factors affect the movement of water within plant cells.