they need carbon dioxide which is in the air on the top rather than the bottom, so it would be on the top.
If a plant did not have stomata on the bottom of its leaves, water and oxygen leaving the plant would not be regulated.
on the top so there would be less water loss
because if it were on the top it would be hard for it to breath, like if a human put a blanket over their mouth and tried to breath. the waxy cuticle is on the top, all the water wouldn't be able to even tough the cuticle if it were on the bottom, and the plant would die without carbon dioxide
as the stomata is responsible in gas exchange, and it constantly looses water through it the stomata would die out
If the stomata were smaller then CO2 would diffuse into the cell less rapidly.
As the upper surface is covered with a waxy cuticle which protects the plant from dehydration if the stomata were covered by a cuticle they would not be able to function.
It is found on the top because the bottom is submerged in water.
Opening and closing of stomata is regulated by concentration of water in guard cells. When transpiration is required, water reaches the guard cells and they swell up. This opens the stomata's pore. When they are not required to be opened, water is not present in guard cells and they shrink causing stomata's pore to close.
More than likely the radiator fan resistor has gone bad. It is located at the bottom corner of the radiator.
sedimentary
they close to conserve water
They close to conserve water.