The pulling force in the plant body that develops at the top of a tree is caused by:

Steward's theory of stomatal opening and closure assumes the presence in the guard cells of which of the following enzymes?

Guttation occurs through . . . . . . .

In darkness,the stomata close because:

Root pressure exceeds over transpiration pull during

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.