1. plants need to cool down when temperature is high.
transpiration ( which is a form of evaporation) cools the plants down.

2.Transpiration facilitates the ascent of sap as the water transpired produces a suction pull in the leaves which leads to the ascent of water through Xylem from roots to the leaves.

NOTE : If it is a 2 mark question WRITE BOTH POINTS.
             If it is a 1 mark question  WRITE SECOND POINT ONLY.
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Transpiration is the process by which plant lose water through the stomata.
It is considered as an evil because excessive loss of water tend to hamper with the photosynthetic process of plants by closing the stomatas.
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