Page 192 - PG 101-Course notes مذكرة النظري 24-25 with spec

Medicinal plants (PG 101) Level 1 Clinical Pharmacy-PharmD

A major examples of osmosis :

• Absorption of water by plant roots.

Osmosis and Plant Cells

(a) Plant Cells in a hypotonic (= weaker) solution – cells have lower water potential

1. The plant cells gain water by osmosis.

2. The vacuole and cytoplasm increase in volume.

3. The cell membrane is pushed harder against the cell wall causing it to stretch

a little.

4. The plant tissue becomes stiffer (= turgid).

(b) Plant Cells in a hypertonic (=stronger) solution – cells have higher water

potential

1. The plant cells lose water by osmosis.
2. The vacuole and cytoplasm decrease in volume.

3. The cell shrinks away from the cell wall.
4. Shrinkage stops when the cell sap is at the same concentration as the external

solution.

5. The plant tissue becomes flaccid, it has shrunk slightly

6. May go on to become plasmolysed.

162