Hypertonic Quiz
Questions: 16 · 10 minutes
1. Compartments A and B are separated by a membrane permeable to water but not to the dissolved solute. B has the higher solute concentration. What is the initial net movement of water?
From B to A because B contains more solute.
From A to B because water moves toward the higher effective solute concentration.
There is no net movement until solute crosses the membrane.
Water leaves both compartments and enters the membrane.
2. In an isotonic environment, how does water typically move across a cell membrane?
Water stops crossing the membrane entirely.
Water moves only out of the cell.
Water moves only into the cell.
Water moves both ways, with no sustained net movement.
3. A nonpenetrating solute is added to the fluid surrounding a cell, raising the external effective solute concentration above the internal concentration. How has the external fluid changed?
It has become hypotonic, so water will enter the cell.
It remains isotonic because only cell solutes determine tonicity.
It has become hypertonic, so water will tend to leave the cell.
It has become pure water despite the added solute.
4. A red blood cell is transferred from an isotonic saline solution to a more concentrated solution of a nonpenetrating solute. Which direction will water move overall?
Into the cell from the surrounding solution.
Out of the cell and into the surrounding solution.
In neither direction because water cannot cross the membrane.
First inward and then permanently stop, regardless of concentration.
5. A plant cell is placed in a hypotonic solution and its cell wall remains intact. Which condition is most likely?
The cell loses all turgor because water exits.
The membrane separates from the wall through plasmolysis.
The cell necessarily lyses in the same way as an animal cell.
The cell becomes turgid as water enters and internal pressure rises.
6. A solution has the same osmolarity as a cell, but its main solute crosses the membrane readily. Why might the solution fail to act isotonic over time?
A penetrating solute may enter the cell and fail to maintain the gradient needed for stable cell volume.
Equal osmolarity always makes a solution permanently hypertonic.
Water can move only when all solutes are nonpolar.
Membrane permeability affects diffusion but never affects tonicity.
7. A plant cell loses water after being placed in a strongly hypertonic solution. Which change is most likely?
The cell wall dissolves as water exits.
The central vacuole expands and turgor rises.
The membrane pulls away from the cell wall during plasmolysis.
The cell bursts because the wall draws water inward.
8. An animal cell is placed in a solution containing more nonpenetrating solute than its cytoplasm. What is the expected result?
Solute leaves the cell until the outside solution becomes hypotonic.
Water enters the cell, causing it to swell.
Water leaves the cell, causing it to shrink.
The cell maintains its original volume because solute cannot cross.
9. Two compartments contain equal concentrations of the same nonpenetrating solute and are separated by a membrane permeable only to water. What should occur?
The solute crosses first and pulls water behind it.
Water moves toward whichever compartment has the larger physical volume.
All water moves to one side because the solute cannot cross.
Water moves in both directions without a sustained net shift.
10. Which statement best distinguishes osmolarity from tonicity?
Osmolarity applies only to cells, while tonicity applies only to pure water.
Tonicity counts every dissolved particle, while osmolarity counts only proteins.
Osmolarity predicts cell shape, while tonicity measures solution temperature.
Osmolarity counts dissolved particles, while tonicity emphasizes nonpenetrating solutes and sustained cell-volume effects.
11. A freshwater protist continually expels water using a contractile vacuole. What does this suggest about its environment relative to its interior?
The environment is hypotonic, so water continually enters by osmosis.
The environment is isotonic, so no water enters the organism.
The environment prevents osmosis but forces solute into the organism.
The environment is hypertonic, causing continuous water loss.
12. What commonly happens to an animal cell placed in a sufficiently hypotonic solution?
It gains water and may lyse if swelling becomes extreme.
It shrinks because the solution draws water outward.
It becomes plasmolyzed while keeping the same volume.
It actively converts the surrounding solution to an isotonic one.
13. Under a microscope, red blood cells appear crenated, with shrunken and irregular edges. Which surrounding condition best explains this?
A hypotonic solution caused sustained water entry.
A hypertonic solution caused net water movement out of the cells.
A solution of pure water caused nonpenetrating solutes to leave.
An isotonic solution prevented water from moving in either direction.
14. What does it mean for a solution to be hypertonic relative to a cell?
It has a higher effective concentration of nonpenetrating solutes than the cell interior.
It contains more water molecules than the cell interior.
It has exactly the same total volume as the cell.
It allows every dissolved solute to cross the membrane freely.
15. A researcher knows that a test solution and a cell have equal total osmolarity, but does not know whether the solution's solutes can cross the membrane. What can the researcher conclude about tonicity?
The solution must be isotonic because equal osmolarity always prevents volume change.
The solution must be hypertonic because external solutes always remain outside.
Tonicity cannot be determined without information about solute permeability.
The solution must be hypotonic because cells always contain proteins.
16. A healthy mammalian red blood cell is placed in a conventionally isotonic 0.9% sodium chloride solution. What is the expected volume response?
It should steadily shrink because all saline solutions are hypertonic.
It should maintain approximately the same volume because there is no sustained net water shift.
It should rapidly burst because sodium chloride enters faster than water.
It should alternate repeatedly between swelling and shrinking.