Turgidity
- ICSE Class 10, Unit 2 Plant Physiology
Turgidity is the firm, swollen state of a plant cell that has taken in so much water that its contents press on the cell wall.
Water enters the vacuole by endosmosis. The swelling contents push outward on the wall. This push is turgor pressure. The wall pushes back with an equal force, called wall pressure. The two act in opposite directions, and the cell becomes stiff.
A cell that has lost water and gone soft is flaccid. Turgid cells hold up soft stems and leaves. When leaf cells turn flaccid, the plant wilts.
A small example
A potted plant in the hot afternoon sun can droop even in wet soil. It loses water faster than its roots take it in. Moved into the shade, it catches up. Its cells fill with water, and the leaves stand firm again.
Where marks go
The 2025 ICSE Biology paper had an assertion-reason question on a turgid cell. Its reason said turgor pressure and wall pressure are equal "and in the same direction". That part is false. CISCE's report on the 2025 ICSE Biology paper lists "turgor and wall pressure acting in opposite directions" among the concepts candidates confused.
Diagrams carry marks too. The ICSE 2027 specimen paper asks for a labelled turgid root hair cell, for 3 marks. A marking scheme gives marks for correct, named labels, such as the vacuole and the cell wall.
Sources
Facts last checked against these sources on 30 September 2026.
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