Biology : PU-CET (U.G) 2018 Panjab University Entrance Exam With Answers

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19.

Tension In Water Column In The Xylem Is Responsible For Water Transport Upward In The Stem, It Means

A: Positive Pressure Potential
B: Negative Pressure Potential
C: Positive Solute Pressure
D: Water Potential Is Zero

The answer is: B

Explanation

B: Negative Pressure Potential.

Tension in the water column in the xylem is created by transpiration, the process by which water is evaporated from the leaves, creating a negative pressure potential that pulls water upward through the stem. This negative pressure potential is also referred to as tension or suction. Water potential, which is the overall potential energy of water in a system, is affected by several factors including pressure potential, solute potential, and gravity. However, in this case, it is the negative pressure potential created by transpiration that is responsible for the upward movement of water in the stem.