Generally,stomata are found on the lower surface of a leaf. Thus,the approximate percentage of transpiration through the abaxial surface is: (in $\%$)

$A-$ The inner wall of each guard cell,towards the pore or stomatal aperture,is thick and elastic.
$R -$ Cellulose microfibrils are oriented longitudinally in the cell walls of the guard cells.

When the relative humidity of the atmosphere is $100\%$ during the daytime,the stomata shall:

Transpiration is the manifestation of

In darkness,the stomata close because:

The factor, most important in regulating transpiration, is