Topic 4.6: Water Potential Questions

State the relationship between the water potential, solute potential and pressure potential of a plant cell.

In a plant cell, the water potential (Ψ) is equal to which of the following?

What does the osmolarity of a solution measure?

Which term describes a plant cell that has lost so much water that its cytoplasm and membrane have pulled away from the cell wall?

State the term used to describe a solution that has a higher osmolarity than the cell it surrounds.

Red blood cells placed in a solution are seen to shrink and develop a wrinkled, spiky surface. What is this shrivelled appearance called?

How do dissolved solutes inside a plant cell affect its water potential?

A plant cell sits in a solution that is the same concentration as its cytoplasm (an isotonic solution). What is its state?

What effect does adding more solute to a solution have on its water potential?

A plant cell is placed in a solution that is more dilute than its cytoplasm (a hypotonic solution). What happens to the cell?

Describe what happens to a cheek cell when it is placed in a concentrated (hypertonic) salt solution.

State the term used for a plant cell that has taken in water and become firm, with its contents pressing hard against the cell wall.

A solution has a higher osmolarity than the cell it surrounds. What is this solution described as?

State the direction in which water moves by osmosis, in terms of water potential.

What is osmosis?

Draw and label a diagram to show the net movement of water for a plant cell in a hypotonic solution and for a plant cell in a hypertonic solution. State the cell state that results in each case.

Micrographs show that red blood cells became shrunken and wrinkled after the salt concentration of the surrounding fluid was changed. Deduce how the salt concentration of the fluid must have changed, giving a reason.

What is solvation?

A sample of red blood cells is divided and added to two solutions. In solution A the cells swell and then burst; in solution B the cells shrink and their surfaces become wrinkled. Explain, in terms of osmosis and tonicity, what has happened to the cells in each solution.

A cell has an internal osmolarity of 290 milliosmoles per litre. It is placed in a solution of osmolarity 290 milliosmoles per litre. State the tonicity of the solution relative to the cell, and calculate the difference in osmolarity between the cell and the solution. Use your answer to predict the net movement of water.