D2.3.10 Contributions of solute potential and pressure potential to the water potential (HL) | Quizlet

What is water potential (ψw)?

Water potential (ψw) is a measure of the free energy of water in a system, influencing water movement.

How is water potential calculated?

Water potential is calculated using the equation ψw = ψs + ψp.

What does ψs represent in the water potential equation?

ψs represents solute potential, which measures the effect of solutes on water's potential energy.

What is the effect of adding solutes on water potential?

Adding solutes lowers water potential because solute molecules bind to water, reducing its ability to move freely.

What is the range of solute potential values?

Solute potential is always negative or zero, with more concentrated solutions having lower (more negative) values.

What does a solute potential of −0.8 MPa mean?

It means the solutes inside the cell reduce its water potential by 0.8 MPa compared to pure water.

What is pressure potential (ψp)?

Pressure potential (ψp) reflects the physical pressure exerted on water.

What causes pressure potential in plant cells?

Pressure potential is caused by the cell wall pushing back against the expanding cell membrane.

What is the typical value of pressure potential in living cells?

Pressure potential is usually positive in living cells.

Give an example of pressure potential in a turgid plant cell.

A turgid plant cell might have a pressure potential of +0.5 MPa, meaning the cell wall exerts positive pressure on the water inside.

What happens to water potential in a hypertonic solution?

In a hypertonic solution, water moves out of the cell, reducing the pressure potential and causing the cell to become flaccid or plasmolysed.

How do solute potential and pressure potential differ?

Solute potential is always negative or zero, while pressure potential is usually positive in living cells.

Can pressure potential be negative?

Yes, pressure potential can be negative in xylem vessels where water is under tension.

What causes tension in the water column of xylem vessels?

Tension in the water column of xylem vessels is caused by transpiration.

Why is understanding water potential important for plants?

Understanding water potential is crucial for explaining how plants maintain turgor pressure, which supports structure and drives growth.

What is the water potential of pure water at standard conditions?

The water potential of pure water at standard conditions is 0 kPa.

What happens to the water potential of a cell when it becomes turgid?

In a fully turgid cell, the pressure potential balances the solute potential, making the water potential equal to zero.

What are the units for measuring water potential?

Water potential is measured in kilopascals (kPa) or megapascals (MPa).

What is the relationship between solute potential and concentration?

More concentrated solutions have lower (more negative) solute potential values.

What does a solute potential of 0 MPa indicate?

A solute potential of 0 MPa indicates that the solution is pure water with no solutes.