AP Biology Water Potential Problems

Front

What is water potential?

Back

Water potential is the potential energy of water in a system compared to pure water, measured in bars. It determines the direction of water movement.

Front

What are the two main components of water potential?

Back

The two main components of water potential are solute potential (osmotic potential) and pressure potential.

Front

How is solute potential calculated?

Back

Solute potential (Ψs) can be calculated using the formula Ψs = -iCRT, where i is the ionization constant, C is the molar concentration, R is the pressure constant (0.0831 liter bar per mole per Kelvin), and T is the temperature in Kelvin.

Front

What is pressure potential?

Back

Pressure potential (Ψp) is the physical pressure exerted on a solution, which can be positive (turgor pressure in plant cells) or negative (tension in xylem).

Front

If a cell has a water potential of -1.5 bars and is placed in a solution with a water potential of -4 bars, which way will water move?

Back

Water will move out of the cell, from an area of higher water potential to an area of lower water potential.

Front

What happens to a plant cell in a hypertonic solution?

Back

In a hypertonic solution, water moves out of the plant cell, causing it to lose turgor pressure and potentially undergo plasmolysis.

Front

What is the effect of placing a plant cell in distilled water?

Back

Placing a plant cell in distilled water (hypotonic solution) causes water to move into the cell, increasing turgor pressure and making the cell swell.

Front

How do you determine the direction of water movement between two solutions?

Back

Water moves from an area of higher water potential to an area of lower water potential.

Front

What is the water potential of a cell with a solute potential of -12 bars and a pressure potential of 3 bars?

Back

The water potential (Ψ) is calculated as Ψ = Ψs + Ψp, so Ψ = -12 bars + 3 bars = -9 bars.

Front

What is the relationship between solute potential and water potential?

Back

Solute potential is a component of water potential; it contributes to the overall water potential of a solution.