Question

Root pressure is maximum when

• A. Transpiration is high and absorption low
• B. Transpiration is very low and absorption is high
• C. Transpiration is very high and absorption is high
• D. Transpiration and absorption both are slow

Answer 1

The correct option is B Transpiration is very low and absorption is high

Root pressure is the positive pressure that develops in the roots of the plants by active absorption of nutrients from the soil. The active absorption depends on the active accumulation of solute in xylem sap. Root pressure in maximum when transpiration is very low and absorption is high because transpiration is the output of water from a plant, and absorption is the input of water into a plant. If the output is low and input is high, the pressure will be at its greatest.

So, the correct answer is 'Transpiration is very low and absorption is high'.