Answers to Hands-on Pg 6-8

Beginning of activity - Apparatus with a porous pot

End of activity - Apparatus with a porous pot

Beginning of activity - Apparatus with a leafy shoot

End of activity - Apparatus with a leafy shoot

Discussion:

1. Water evaporates from the surface of the porous pot, causing the water in the capillary tube to rise. This draws the mercury level up. Adhesive forces and cohesive forces enable the water column to be held together.
2. As the water evaporates from the leaf surface, the water in the xylem vessel rises, drawing the mercury up the capillary tube. Adhesive forces between water molecules and the capillary tube wall prevent the water molecules from falling back. Cohesive forces between the water molecules prevent the water column from breaking.

Conclusion :

Adhesive and cohesive forces cause the movement of water in plants.