Question

Which scientists are credited with proposing the transpiration pull theory, also known as the cohesion-tension theory?

• A. Charles Darwin and Francis Darwin
• B. Stephen Hales
• C. Henry Dixon and John Joly
• D. Ernst Münch

Hint:

The cohesion-tension theory relies on the cohesive and adhesive properties of water molecules and the role of transpiration in creating negative pressure to pull water upward in plants.

Answer 1

The Correct Option is D

Step 1: Understanding the transpiration pull theory The transpiration pull theory, also known as the cohesion-tension theory, explains the movement of water from roots to leaves in tall plants. It attributes this upward movement to: Cohesion of water molecules (water-water attraction) Adhesion of water molecules to xylem walls Negative pressure (tension) generated due to transpiration from leaves Step 2: Contribution of Ernst Münch Ernst Münch is credited with proposing the cohesion-tension theory. His work highlighted the role of transpiration in generating a pulling force and the cohesive nature of water in enabling the upward flow through the xylem vessels. Step 3: Elimination of incorrect options (A) Incorrect: Charles Darwin and Francis Darwin contributed to understanding plant tropisms but not the cohesion-tension theory. (B) Incorrect: Stephen Hales made significant contributions to plant physiology, especially in water uptake, but did not propose this theory. (C) Incorrect: Henry Dixon and John Joly are associated with early explanations of water transport but are not credited with the cohesion-tension theory.