Question 1

Which of the following best describes the direction of water movement in plant cells when placed in a hypertonic solution?

Accepted Answer

Water moves out of the cell, causing plasmolysis.

Question 2

Given the equation $$\Psi = \Psi_s + \Psi_p$$, what is the water potential ($$\Psi) of $$pure water in an open container?

Accepted Answer

$$\Psi = 0$$

Question 3

A plant cell is placed in a solution and does not change in mass. What can you conclude about the water potential of the solution compared to the cell?

Accepted Answer

The solution and the cell have equal water potentials.

Question 4

Calculate the solute potential ($$\Psi_s) of a 0.2 M $$sucrose solution at 25°C. Use $$i = 1$$, $$R = 0.0831 L$$·bar/mol·K, and $$T = 298 K.$$

Accepted Answer

$$\Psi_s = -4.96$$ bars

Question 5

Which of the following statements about water potential is correct?

Accepted Answer

Water moves from areas of high water potential to areas of low water potential.

Question 6

If a potato cube gains mass after being placed in a solution, what can you infer about the tonicity of the solution relative to the potato cells?

Accepted Answer

The solution is hypotonic to the potato cells.

Question 7

A dialysis bag containing a 0.3 M sugar solution is placed in distilled water. What will happen to the mass of the bag after 20 minutes?

Accepted Answer

The mass will increase as water enters the bag.

Question 8

Which equation is used to calculate the solute potential ($$\Psi_s) of a $$solution?

Accepted Answer

$$\Psi_s = -iCRT$$

Question 9

A tree’s roots have a water potential ($$\Psi) of$$ $$-8$$ bars, and the surrounding soil has a water potential of $$-4$$ bars. In which direction will water move?

Accepted Answer

From the soil into the roots

Question 10

Which of the following changes will make the water potential of a solution more negative?

Accepted Answer

Increasing solute concentration

Question 11

A plant cell in a hypotonic solution becomes turgid. What is the main reason for this?

Accepted Answer

Water enters the cell due to higher water potential outside.

Question 12

If the pressure potential ($$\Psi_p) in a $$plant cell increases while solute potential ($$\Psi_s) $$remains constant, what happens to the overall water potential ($$\Psi$$)?

Accepted Answer

Water potential increases.

Question 13

Which of the following best explains why adding salt to soil can harm plants?

Accepted Answer

It decreases the water potential of the soil, causing water to leave the roots.

Question 14

A solution has a solute potential ($$\Psi_s) of$$ $$-5$$ bars and a pressure potential ($$\Psi_p) of$$ $$+2$$ bars. What is the water potential ($$\Psi$$)?

Accepted Answer

$$\Psi = -3$$ bars

Question 15

Which of the following is true about osmoregulation in plant cells?

Accepted Answer

It allows the cell to control its internal solute composition and water potential.

Question 16

A 0.1 M NaCl solution at 25°C has an ionization constant $$i = 2. $$Calculate its solute potential ($$\Psi_s) $$using $$R = 0.0831 L$$·bar/mol·K and $$T = 298 K.$$

Accepted Answer

$$\Psi_s = -4.95$$ bars

Question 17

Which of the following best describes the relationship between solute concentration and solute potential ($$\Psi_s$$)?

Accepted Answer

As solute concentration increases, solute potential becomes more negative.

Question 18

In a diffusion experiment, why do smaller agar cubes clear their indicator faster than larger cubes?

Accepted Answer

They have a higher surface area to volume ratio.

Question 19

If a plant cell is placed in distilled water, what will happen to its pressure potential ($$\Psi_p) $$over time?

Accepted Answer

It will increase as water enters the cell.

Question 20

Which of the following is a correct application of the formula $$\Psi_s = -iCRT$$ for a 0.3 M MgCl$$_2$$ solution at 25°C? ($$i = 3$$, $$R = 0.0831 L$$·bar/mol·K, $$T = 298 K)$$

Accepted Answer

$$\Psi_s = -(3)(0.3)(0.0831)(298)$$

Water Potential and Osmoregulation

Guida di studio - Domande di pratica

Study guide - Flashcard