D2.3.6—Effects on cells with wall
Cells with walls become turgid in hypotonic solutions and plasmolysed in hypertonic solutions as water moves by osmosis across membranes.
- Syllabus
- First assessment 2025
- Objective
- D2.3.6
- Level
- SL
Exam analysis
Chance of appearing1%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper2
Typical marks7
Common command terms
- Outline
- State
- Explain
Scoring notes
- Common mistake
- Saying plant cells burst in hypotonic solution ignores the protective cell wall.
Recent exam appearances
May 2025Paper2 ["SL"] · TZ16(c)[ 7 ]D2.3.6—Effects on cells with wall
Practice this objective
Coverage 2025–2025 · Updated 16 Jul 2026
Cell Walls Limit Swelling and Create Turgor
A cell wall resists expansion when water enters, converting osmotic water uptake into turgor pressure.
The wall’s rigidity balances the inward tendency of water. If water leaves, pressure falls and the membrane can pull away from the wall, producing plasmolysis.
Distinguish wall restraint from membrane transport: water direction first, then pressure and shape.
A plant cell in dilute solution becomes turgid rather than bursting because the wall pushes back as the vacuole expands.
A wall prevents unlimited swelling but does not stop osmosis or guarantee that a severely dehydrated cell survives.
Effects on cells with wall
Assessment in practice
1–4 marksHow it is assessed
This objective is assessed through structured response, commonly using Outline / State / Explain.
Command terms
Outline / State / Explain
What earns marks
Build the answer around this relationship: Water entry can make plant cells turgid.
Watch for
Saying plant cells burst in hypotonic solution ignores the protective cell wall.
Representative question
Question 1
Explain the process of osmosis with reference to its effects on plant cells.
Core Osmosis Effects
Water forms hydration shells around ions and polar solutes; hydrogen bonding and charge attraction reduce free water movement. Water moves by osmosis across partially permeable membranes from hypotonic/lower solute solutions toward hypertonic/higher solute solutions. Osmosis direction depends on internal and external solute concentration; isotonic conditions have dynamic water movement but no net osmosis. Plant tissue changes mass or length in sucrose solutions; percentage change graphs estimate isotonic or osmotic concentration. Animal cells can lyse in hypotonic solutions and crenate in hypertonic solutions; freshwater protists use contractile vacuoles to expel excess water. Plant cells become turgid in hypotonic solutions as vacuoles swell; hypertonic solutions cause flaccidity and plasmolysis from water loss. Isotonic saline prevents harmful water gain or loss in body cells; IV fluids and transplant organ baths must match tissue osmotic concentration.
Concept essentials
- Water entry can make plant cells turgid.
- The cell wall prevents plant cells from bursting under turgor pressure.
- Hypertonic solutions cause water loss and plasmolysis.
- Plasmolysis involves the membrane pulling away from the cell wall.