Question

select the true statements. cohesive forces must be stronger than adhesive forces for capillary action to occur. hydrogen bonding between water molecules holds water together as it moves up xylem cells. adhesion between water molecules and xylem cell walls helps water move vertically in plants. water moving up through xylem cells is not affected by gravity.

Explanation:

1. For capillary action in plants, both cohesive and adhesive forces are important and neither needs to be strictly stronger than the other. So the first statement is false.
2. Hydrogen - bonding between water molecules (cohesive force) holds water together as it moves up xylem cells, which is true.
3. Adhesion between water molecules and xylem cell walls helps counter - act gravity and enables water to move vertically in plants, which is true.
4. Water moving up through xylem cells is affected by gravity, and the combined action of adhesion, cohesion and transpiration pull helps overcome the gravitational force. So the fourth statement is false.

Answer:

Hydrogen bonding between water molecules holds water together as it moves up xylem cells.
Adhesion between water molecules and xylem cell walls helps water move vertically in plants.