Question 1

Which of the following best describes the process of osmosis in biological systems?

Accepted Answer

The movement of water molecules from an area of high water potential to an area of low water potential across a selectively permeable membrane.

Question 2

A plant cell with a water potential $$\Psi = -0.7$$ MPa is placed in pure water ($$\Psi = 0$$ MPa). What will happen to the cell?

Accepted Answer

Water will enter the cell, causing it to become turgid.

Question 3

Which equation correctly represents the calculation of water potential in plant cells?

Accepted Answer

$$\Psi = \Psi_s + \Psi_p$$

Question 4

A solution contains 1.5 mol/L sucrose at 22°C. Calculate the solute potential ($$\Psi_s) $$using the formula $$\Psi_s = -iCRT. ($$Sucrose does not ionize, so $$i = 1$$; $$R = 0.0831 L$$·bars/mol·K; $$T = 295 K)$$

Accepted Answer

$$\Psi_s = -36.77$$ bars

Question 5

If a flaccid plant cell with $$\Psi_s = -0.9$$ bars and $$\Psi_p = 0$$ bars is placed in a beaker with a solution of $$\Psi = -0.5$$ bars, what is the initial water potential of the cell?

Accepted Answer

$$\Psi = -0.9$$ bars

Question 6

In which direction will water move when a cell with $$\Psi = -0.9$$ bars is placed in a solution with $$\Psi = -0.5$$ bars?

Accepted Answer

Water will move out of the cell.

Question 7

Which of the following statements about turgor pressure in plant cells is correct?

Accepted Answer

Turgor pressure is the internal pressure against the cell wall that helps maintain plant structure.

Question 8

Which of the following best describes a hypertonic solution relative to a cell?

Accepted Answer

The solution has a higher solute concentration than the cell.

Question 9

What is the primary function of aquaporins in plant cells?

Accepted Answer

To facilitate the diffusion of water across the membrane.

Question 10

Marine bony fish live in an environment that is hyperosmotic to their body fluids. What osmoregulatory challenge do they face?

Accepted Answer

They tend to lose water and gain solutes.

Question 11

Which of the following mechanisms is NOT a form of passive transport across cell membranes?

Accepted Answer

Active transport using ATP.

Question 12

If a plant cell is placed in a hypotonic solution, what will happen to the cell?

Accepted Answer

It will gain water and become turgid.

Question 13

Which of the following best explains why solute potential ($$\Psi_s) is $$usually negative?

Accepted Answer

Solutes decrease the concentration of free water, lowering water potential.

Question 14

A cell with $$\Psi = -0.3$$ MPa is placed in a solution with $$\Psi = -0.9$$ MPa. What will happen to the cell?

Accepted Answer

Water will move out of the cell, causing it to plasmolyze.

Question 15

Which of the following is true about water movement in plant tissues during transpiration?

Accepted Answer

Water moves from the xylem to the mesophyll cells due to tension created by evaporation.

Question 16

Which of the following statements about osmoregulation in aquatic animals is correct?

Accepted Answer

Freshwater animals are hyperosmotic to their environment and tend to gain water.

Question 17

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

Accepted Answer

$$\Psi_s = -iCRT$$

Question 18

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water.

Question 19

Which of the following is a consequence of increasing the amount of solute in water?

Accepted Answer

Solute potential decreases, making water potential more negative.

Question 20

Which statement best describes the role of osmoregulation in living organisms?

Accepted Answer

Osmoregulation maintains water balance and allows organisms to control their internal solute composition and water potential.

Tonicity and Osmoregulation: Principles and Applications in Biology

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