Question

why does the lower surface of leaf lose more water?

Answer 1

the lower surface lose more water because it has wide open pores for exchange of gases .the pores are called
stomata.

Answer 2

the lower surface of leaf loose more water because more amount of stomata are present on lower epidermis of leaf. and we know that function of stomata is transpiration. so loss of water is more from lower surface of leaf.

I hope it will help you