Question

Why are the number of stomatas present on upper surface of leaves of a leaf are coparetively less than on the lower surface of leaf?

Answer 1

The number of stomatas present on upper surface of leaves of a leaf because leaf do photosynthesis to make their and lot of sunlight observed by upper surface.so upper surface have large number of stomata than lower surface.

Answer 2

The number of stomatas on the leaves are more on the upper surfaces as compared to lower because the process by which green plants make their own food (photosynthesis) are done by leaves and  it requires sunlight for this process and maximum sunlight can only be trapped by the upper part of the leaves.