Given below are two statements, one labelled as Assertion (A) and the other as Reason (R). In the light of the statements, choose the most appropriate answer from the options.
Assertion (A): Transpiration helps in the ascent of sap.
Reason (R): Transpiration increases the osmotic pressure in roots.
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is false but (R) is true
- D(A) is true but (R) is false
Show answer and explanation
Correct answer: (d) (A) is true but (R) is false
Explanation
(A) is true and (R) is false.
- (A): transpiration (evaporation of water from leaves, mainly through the stomata) creates a transpiration pull that draws water up through the xylem. Together with the cohesion of water molecules, this is the main force behind the ascent of sap.
- (R): transpiration does not increase the osmotic pressure in roots. The push from the roots, root pressure, comes from the active uptake of minerals by the roots, which is separate from transpiration.