Question

why do stomata are mostly present in the lower part of epidermis ?

Answer 1

Answer:

The lower epidermis has more stomata to prevent evaporation.

Explanation:

All surfaces of the leaf have some amount of stomata for regulating gas exchange for photosynthesis. However, the lower epidermis (the underside of the leaf) has more, because it is more often in the shade and so it is cooler, which means evaporation won't take place as much. Evaporation would mean the plant loses water, vital for life.