Question

Root pressure develops due to

• A. passive absorption
• B. active absorption
• C. increase in transpiration
• D. facilitated diffusion

Answer 1

The correct option is B active absorption

Active absorption is the movement of ions against the concentration gradient utilizing energy. The mineral ions are actively absorbed into the xylem of the root from the soil, thus the water potential inside root cells decreases when compared to soil.

Water moves from a region of higher water potential to lower water potential without the use of energy.

Hence, there is passive movement of water from the soil into the roots by osmosis. This increases the pressure inside the xylem of the root and is called root pressure.

Therefore root pressure acts as the positive hydrostatic pressure developed in the xylem of the root and is responsible for the ascent of sap.