Question

Assertion (A): Transpiration is the process that is associated with the ascent of sap.
Reason (R): The transpiration process helps in lowering the temperature of the plant.

Answer 1

Answer:

Explanation:

The upward movement of water and minerals in a plant through xylem is called ascent of sap. During transpiration, pressure in the internal roots develop known as root pressure. This root pressure helps in ascent of sap. Thus, transpiration helps in ascent of sap.

Answer 2

Both the assertion and reason are true and the reason is the correct explanation for the assertion.

Explanation:

• The theory states that transpiration pull or tension, cohesion property of water, and hydration of the cell walls (i.e., adhesion) are collectively responsible for the ascent of sap.

• Transpiration pull is the process that is responsible for the ascent of sap.

• Transpiration is a process that involves the loss of water vapor through the stomata of plants.

• The loss of water vapor from the plant cools the plant down when the weather is very hot, and water from the stem and roots moves upwards or is 'pulled' into the leaves.

• Transpiration mainly takes place in the aerial part of the plant; stomata of leaves evaporate high amounts of water in the form of vapor which helps to keep the plant cool.