Question

Why are the stomata in most plants more numerous on the lower surface of a leaf instead of being on the upper surface ?

Answer 1

All surfaces of the leafhave some amount of stomata for regulating gas exchange for photosynthesis. However, the lowerepidermis (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.