DENDROLOGY

Detailed explanation-1: -IAA, or indole-3-acetic acid, is an example of an auxin. Auxins are responsible for directional plant growth in response to a stimulus, a process called tropism. Phototropism, or the growth of a plant in response to a light stimulus, is controlled by auxins.

Detailed explanation-2: -Auxins also play a part in phototropism, an occurrence that involves plants bending or moving away from light. The shoot tip is responsible for directional movement by the plant in response to sunlight, as this is the area where auxins can be found.

Detailed explanation-3: -Auxins are a group of naturally occurring and artificially synthesised plant hormones. They play an important role in the regulation of plant growth. Auxins were initially isolated from human urine. Auxin means to “enlarge” or “increase”.