Question

Which of the following best describes the widely accepted root pressure theory in plants?

• A. It explains the mechanism of water movement through transpiration pull.
• B. It describes the active uptake of minerals from the soil.
• C. It refers to the pressure exerted by roots to push water upwards through the xylem.
• D. It relates to the diffusion of gases in plant cells.

Hint:

Root pressure is particularly important in small plants and during the early stages of plant growth, helping to maintain water flow in the absence of strong transpiration forces.

Answer 1

The Correct Option is C

The root pressure theory elucidates the process by which plants conduct water from their roots to their shoots, independent of sole reliance on transpiration pull. This pressure originates from the active transport of ions into the root xylem. Consequently, the water potential decreases, prompting water to migrate into the xylem from the surrounding soil via osmosis. This resultant water influx establishes a positive pressure, which propels water upward through the xylem vessels.
Mechanism of Root Pressure: \[ \text{Transport of Ions} \rightarrow \text{Lowered Water Potential} \rightarrow \text{Water Uptake by Osmosis} \rightarrow \text{Positive Pressure} \]
Conclusion: Root pressure is a crucial process that facilitates the ascent of water, particularly when transpiration rates are diminished, such as during nocturnal periods.