THE EXAMS POINTThree osmotic situations
Begin at the centre. Explore a branch, explain its connection, then test your recall. Tap any branch heading to fold or expand it.
In recall mode, focus or tap a branch to reveal its explanation. Branches group related ideas; they do not imply a chronological sequence.
Three osmotic situations
01 · Hypotonic outside
Net water entry into the cell; an animal cell may swell and lyse.
02 · Isotonic outside
No net water movement; water still moves in both directions.
03 · Hypertonic outside
Net water exit; animal cells shrink and plant cells may plasmolyse.
Connect the branches
Compare the effective concentrations of non-penetrating solutes across a selectively permeable membrane. This is a simplified school-level model.
Avoid the exam trap
Isotonic does not mean that water molecules stop moving.
Test yourself: Which condition can produce plasmolysis in a plant cell?
A sufficiently hypertonic external solution causes net water loss and separation of the protoplast from the wall.
A concise revision aid with simplified connections. It supports the full chapter and primary references; it does not replace them.