2023 · Q46
Water goes up through xylem vessels in tall trees. The process in plants and properties of water that help in upward movement are:
General KnowledgeBiology
- ARespiration and cohesion.
- BTranspiration pull, cohesion and adhesion.
- CRoot pressure, cohesion and adhesion.
- DTranspiration and adhesion.
Explanation
The ascent of sap is explained by the cohesion-tension theory of Dixon and Joly: transpiration from the leaves creates a pull, the cohesion of water molecules holds the continuous water column together, and adhesion to the xylem walls supports it. Root pressure alone cannot lift water to the tops of tall trees.