Download Problems water potential

NAME: ____________________________DATE: __________ BLOCK: ____
TRUE OR FALSE
1.
When water moves into a turgid cell, the Ψp of the cell remains constant.
2.
When the solute concentration of a cell increases, Ψs decreases. (Assume that the
volume remains the same.)
3.
Cell A has a Ψ of –1.1 MPa and cell B has a Ψ of –0.9 MPa. If the two cells are brought
into contact with one another, water will move from cell A into cell B.
Ψ PROBLEMS
4.
The Ψs for a leaf from a well-watered plant is measured to be –0.4 MPa and the Ψp is
estimated to be 0.2 MPa. Find the Ψ of the leaf.
5.
The same plant is exposed to mild water stress. The pressure potential drops to 0.1
MPa. Assume Ψs does not change. Find the Ψ of the leaf.
6.
In response to water stress, the solute concentration in the cells of the leaf increases
bringing Ψs to –0.6 MPa. Find the Ψ of the leaf.
7.
The water potential of a sugar beet root is measured to be –2.1 MPa and the Ψs is –2.5.
Calculate the Ψp.
8.
An algal cell with the Ψs of –0.42 MPa is living in a pond with Ψs of –0.11 MPa.
Assuming that the algal cell is in equilibrium with its environment, what is its pressure
potential? If you had microscopic fingers and could gently squeeze this algal cell, would it
feel firm or limp?
9.
A closed, sac-like membrane, filled with a solution that has solute potential of –2.2 MPa,
is immersed in a solution with Ψs of –0.8. Assume that the membrane is permeable to
water only, and that the solute potentials will not change with osmosis. What will be the
Ψs, Ψp, and Ψ of the internal solution at equilibrium?
10. Cell A is immersed in a solution with an osmotic pressure of 0.3 MPa. Cell B is
immersed in a solution with an osmotic pressure of 0.5 MPa. The cells are allowed to
come to equilibrium in their respective solutions. Then the cells are removed and brought
into intimate contact. In which direction will there be net water movement, from cell A to
cell B or from cell B to cell A?
EXTRA CREDIT
11. Cells X, Y, and Z form a chain. The solute potentials (Ψs) are as follows: Cell Z is -1.0,
Cell Y is -0.9, and Cell X is -1.5 (see picture below). The lowest cell, Z, dips into a
solution with a Ψs of –0.7 MPa. At equilibrium, what will the Ψs, Ψp, and Ψ of each cell
be? Put the values in Table 1.
Location
Cell Z
Cell Y
Cell X
Ψs
Ψp
Ψ