Question 1

Which of the following best describes osmosis?

Accepted Answer

The movement of water molecules from an area of low solute concentration to an area of high solute concentration through a selectively permeable membrane.

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome?

Accepted Answer

The cell will gain water and burst (lyse).

Question 3

Which of the following statements about plant cells in a hypertonic solution is correct?

Accepted Answer

The cell will lose water, and the plasma membrane will pull away from the cell wall (plasmolysis).

Question 4

Which of the following best explains why saltwater fish must actively excrete salt through their gills and kidneys?

Accepted Answer

They live in a hypertonic environment and must prevent dehydration by removing excess salt.

Question 5

A plant cell is placed in a 0.2 M sucrose solution at 20°C. Calculate the solute potential ($$\Psi_s) of $$the solution using the formula $$\Psi_s = -iCRT. ($$Assume $$i=1$$, $$C=0.2$$ mol/L, $$R=0.0831 L$$·bar/mol·K, $$T=293 K.)$$

Accepted Answer

$$\Psi_s = -4.87$$ bars

Question 6

If the water potential ($$\Psi) of $$root tissue is $$-4.6$$ bars and it is placed in a solution with $$\Psi = -4.87$$ bars, in which direction will water move?

Accepted Answer

Water will move out of the root tissue into the solution.

Question 7

Which of the following is true about isotonic solutions?

Accepted Answer

There is no net movement of water into or out of the cell.

Question 8

A beaker contains a 0.3 M sugar solution at 27°C in open air. Calculate the solute potential ($$\Psi_s) $$using $$\Psi_s = -iCRT$$ ($$i=1$$, $$C=0.3$$ mol/L, $$R=0.0831 L$$·bar/mol·K, $$T=300 K).$$

Accepted Answer

$$\Psi_s = -7.48$$ bars

Question 9

Which of the following best describes the movement of water in terms of water potential ($$\Psi$$)?

Accepted Answer

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

Question 10

Which adaptation helps saltwater fish survive in a hypertonic environment?

Accepted Answer

Actively pumping out excess salt through specialized cells in their gills.

Question 11

A plant cell is placed in pure water. Which of the following best describes what happens and why?

Accepted Answer

The cell gains water, becomes turgid, and is supported by its cell wall.

Question 12

Which of the following is the correct formula for calculating solute potential ($$\Psi_s$$)?

Accepted Answer

$$\Psi_s = -iCRT$$

Question 13

A freshwater protist living in a hypotonic environment uses a contractile vacuole. What is the main function of this organelle?

Accepted Answer

To pump excess water out of the cell to prevent lysis.

Question 14

Which of the following best explains why plant cells do not burst in hypotonic solutions?

Accepted Answer

Their cell wall provides structural support and limits excessive water uptake.

Question 15

If a cell with a solute concentration of 0.15 M NaCl is placed in a 0.3 M NaCl solution, what will happen to the cell?

Accepted Answer

Water will leave the cell, causing it to shrink.

Question 16

Which of the following is NOT a component of water potential ($$\Psi$$)?

Accepted Answer

Temperature potential ($$\Psi_t)$$

Question 17

A plant cell is placed in a solution with a higher water potential than the cell's interior. What will happen?

Accepted Answer

Water will move into the cell, increasing turgor pressure.

Question 18

Which of the following best describes the role of transpiration in plants?

Accepted Answer

It creates negative pressure that pulls water upward from the roots through the xylem.

Question 19

Which of the following is a correct statement about water movement in the context of water potential?

Accepted Answer

Water moves from areas of high water potential (less negative) to areas of low water potential (more negative).

Tonicity & Osmoregulation: Water Balance in Cells

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