The ultimate force which propels water against gravity is generated by

What is the stomatal apparatus? Explain the structure of stomata with a labelled diagram.

Which one gives the most valid and recent explanation for stomatal movement?

Read the following statements carefully and choose the right answer from the codes given below:
$I$. $PMA$ and silicon oil of low viscosity are considered as antitranspirants.
$II$. $BAP$,$NAA$,and cobalt chloride are also used as antitranspirants.
$III$. Abscisic acid $(ABA)$ affects the mechanism of opening and closing of stomata.
$IV$. Starch of guard cells is converted into $PEP$ (phosphoenolpyruvate) ions by the process of hydrolysis.
$V$. Potometer works on the principle of potential difference between the tip of the tube and that of the plant.
$VI$. Transpiration rate is directly proportional to the relative humidity.

The basis of stomatal opening is:

Stomata open because of