Question

Root pressure theory of ascent of sap is unacceptable because

• A. Water can ascend without root or root pressure.
• B. Root pressure cannot explain ascent of sap beyond 10 meters.
• C. Root pressure is more during early morning than afternoon.
• D. Root pressure does not occur in spring.

Answer 1

Answer: (A)

Water can ascend without root or root pressure.

This theory was proposed by Priestley. Root pressure is the pressure which is set up in the cortical cells of the roots due to osmotic action and forces water up the xylem vessel. This theory is unacceptable because ascent of sap was also observed in plants in which roots were removed.

So the correct answer is 'Water can ascend without root or root pressure'.