Question 1
Multiple choiceMedium1 markIn a plant, the rate of water loss from leaf-cell walls increases. Which change in the xylem and role of cohesion are expected?
Show answer and explanation
Answer: B. Water loss from leaf-cell walls draws water out of the xylem through the cell walls, increasing tension (making the pressure potential more negative). Cohesion keeps water molecules connected in a continuous column, allowing this tension to draw water upward.
A: reverses the direction of water movement, so it incorrectly predicts reduced tension.
C: has the correct movement and tension but reverses the role of cohesion.
D: gets the water movement right but reverses the pressure change; tension is negative pressure potential.
Remember: transpiration creates tension, while cohesion maintains the continuous water column.