Question

Root pressure is maximum when:

• A. Transpiration is high and absorption is very low
• B. Transpiration is very low and absorption is high
• C. Transpiration is very high and absorption is also high
• D. Both transpiration and absorption are low

Answer 1

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

Root pressure in plants is a force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just above ground. Root pressure is 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.