Phytohormones control:

The leaf of $Mimosa$ $pudica$ droops down upon touching due to:

The least porous soil among the following is a

Differentiate between the following plant growth regulators:
$(1)$ Auxins $(IAA)$ and Abscisic acid $(ABA)$
$(2)$ Gibberellins and Ethylene

$I.$ Kinetin is a degradative substance from $DNA$.
$II.$ $ABA$ is present in all plants including lower plants.
$III.$ Low ratio of cytokinin to auxin favours root formation only.
$IV.$ $ABA$ is synthesized catabolically through glycolysis pathway.
Choose the correct combination of options.

Factors which can modify geotropic responses are