Question

When a stem of a plant is cut a few inches above the soil and xylem sap is seen flowing out through the cut end, this exudation is considered evidence for the existence of root pressure. Who proposed the theory of root pressure?

• A. Robert Hooke.
• B. Stephen Hales.
• C. Joseph Priestley.
• D. Gregor Mendel.

Hint:

Root pressure is a key concept in plant physiology and helps explain how water and nutrients move from roots to shoots in the absence of transpiration.

Answer 1

The Correct Option is C

Step 1: Understanding root pressure. 
Root pressure is the hydrostatic pressure generated in the roots due to active absorption of water and minerals from the soil. It causes the upward movement of xylem sap. 
Step 2: Historical perspective. 
The theory of root pressure, along with observations of sap exudation, was proposed and studied by Joseph Priestley. This phenomenon highlights the role of osmotic gradients in water transport within plants. 
Step 3: Explanation of other options. 
Robert Hooke: Known for his contributions to cell theory, not root pressure. 
Stephen Hales: Known for his studies on plant physiology but did not propose the theory of root pressure. 
Gregor Mendel: Father of genetics, unrelated to root pressure.