Question

why is transpiration is a neccessary evil

Answer 1

It is said because if the water which is not for use is not thrown out if the body ,the plant can not take more water from the ground

Answer 2

Transpiration is a necessary evil because at the good side it helps the minerals and nutrients collected by the root and transports it to the leaves that Futher make food out of them and it also helps the water to reach every part of the plant at the bad side transpiration takes 90% of the water in evaporation and only 10% remains with the plant.

Hope it helps,
Suhani