Leaf fall occurs when the abscission layer is formed due to a change in the content of:

Geotropic response of roots is due to

Dr. $F$. Went noted that if coleoptile tips were removed and placed on agar for one hour,the agar would produce a bending when placed on one side of freshly-cut coleoptile stumps. Of what significance is this experiment?

Give scientific reasons: Indole-$3$-acetic acid $(IAA)$ is not the only naturally occurring auxin.

The primary precursor of $IAA$ is

What is the precursor of $IAA$?