Question

Root pressure does not take an active part in the ascent of sap because

• A. It is not found in all the plants and water can rise in the absence of root.
• B. It is seen during most favourable periods like spring or rainy season.
• C. It is never found to exist in the plants.
• D. Both A and B.

Answer 1

Answer: (D)

Both A and B.

Root pressure is defined as pressure developing in the tracheary elements of xylem due to metabolic activities of the root. The pressure is caused due to diffusion pressure gradient and is maintained by the activity of living cells. It is believed that root pressure is largely responsible for the ascent of sap in herbaceous plants and the pressure develops more in certain seasons especially rainy season in tropical and spring season in temperate habitats which favour optimum metabolic activity and reduce transpiration. The magnitude of root pressure is about 2 bars only.

Thus, the correct answer is option D.