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eMusic Study Pack • Biology
Student
📖 Comprehensive Note
Isotonic solution — an environment where the solute concentration (and therefore water potential) is essentially equal to that of the cell sap. In an isotonic solution there is no net movement of water across the cell membrane by osmosis because the amount of water entering equals the amount leaving.
- Cells maintain normal shape and volume in isotonic conditions.
- Plant cells may be flaccid (not turgid) but are not plasmolysed in truly isotonic media.
- Animal cells (e.g., red blood cells) remain stable — neither shrinking (crenation) nor bursting (haemolysis).
- 0.9% saline is isotonic to human red blood cells and is commonly used medically to preserve cell integrity.
🎤 Lyrics
Verse 1
When a cell is placed
in an isotonic solution,
There is no net movement
of water into or out of the cell.
Oh oh oh oh oh oh oh
The amount of water
entering the cell is equal to
the amount leaving the cell. Uhhhhh uhhhh uhhh yea
Chorus
Uh uh uh uh yeah yeah
An isotonic solution
is a solution that has the
same solute concentration yeah ah ah
and the same water potential
as the cell sap of a living cell!...living cell
Verse 2
The cell retains its normal shape and size.
In plant cells,
the cell remains flaccid
but not plasmolysed. - not plaasmolysis
In animal cells,
the cell remains normal
without shrinking or bursting.
Chorus
Uh uh uh uh yeah yeah
An isotonic solution
is a solution that has the
same solute concentration yeah ah ah
and the same water potential
as the cell sap of a living cell - living cell
Outro
0.9% salt (saline) solution is
isotonic to human red blood cells.
Hmmmmhmmmmmmhmmmhmm
An isotonic solution maintains
the normal shape of cells,
because there is no net
movement of water by osmosis.
Chorus
Uh uh uh uh yeah yeah
An isotonic solution
is a solution that has the
same solute concentration yeah ah ah
and the same water potential
as the cell sap of a living cell
A living cell.....a living....cell
0:00
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📊 Line-by-Line Study Guide
| Lyric Line | Explanation |
|---|---|
| When a cell is placed in an isotonic solution | External solute concentration and water potential are equal to the cell's internal environment, so no net water movement occurs. |
| The amount of water entering equals leaving | Water molecules move in and out at equal rates; dynamic equilibrium is maintained. |
| Plant cells remain flaccid but not plasmolysed | In isotonic media plant cells lack turgor (not turgid) but do not undergo plasmolysis (membrane detachment) as occurs in hypertonic media. |
| 0.9% saline is isotonic to RBCs | Medical saline prevents haemolysis or crenation by matching blood osmolarity. |
| Isotonic maintains normal cell shape | Homeostasis of cell volume is preserved in isotonic conditions. |
🔬 Demonstrations & Classroom Notes
- Demonstration idea: compare onion epidermis in distilled, isotonic (saline), and concentrated salt solution to show turgid, flaccid (isotonic), and plasmolysed states.
- 0.9% saline is a safe isotonic fluid used clinically; never substitute without guidance in lab demos involving animals.
- Observe red blood cells under microscope in isotonic saline to see stable, normal shapes.
💡 Mnemonic
"ISO = SAME" — Isotonic means “same” solute concentration/water potential as the cell (no net water change).
❓ Quiz
1. An isotonic solution has:
2. What happens to RBCs in 0.9% saline?
3. Plant cells in isotonic solution are usually:
4. Isotonic =
🃏 Flashcards
Q: Define isotonic solution.
A solution with the same solute concentration and water potential as the cell; no net water movement by osmosis.
Q: Give an example isotonic solution for human cells.
0.9% saline (physiological saline) is isotonic to human red blood cells.
🎯 Drag & Drop
Drag each phrase into the correct box.
Isotonic Effects
Not Isotonic / Opposite
Examples
No net water movement
Cell becomes turgid
0.9% saline (RBCs)
Cell undergoes plasmolysis
📌 Summary
- Isotonic: equal solute concentration/water potential between cell and environment → no net osmosis.
- Cells keep normal shape: animal cells stable; plant cells flaccid (not plasmolysed) if exactly isotonic.
- 0.9% saline is a common isotonic solution for red blood cells.