Question

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. Which of the following is the significance of this experiment?
A. It made possible the isolation and exact identification of auxin.
B. It is the basis for the quantitative determination of small amounts of the growth-promoting substances.
C. It supports the hypothesis that IAA is auxin.
D. It demonstrated polar movements of auxins.

Answer 1

All plants require temperature, air, water, light, nutrients, time, room to grow these seven essential factors to grow a plant. Plants promoter, they promote cell division, expansion of cells, flowering, fruiting and seed development. Example: auxins, gibberellins, cytokines

Complete answer:
Isolation and identification of auxins this is not a sign of this experiment.
So the option (A) is incorrect.
It is the basis for the quantitative determination of small amounts of the growth-promoting substance; this is not a correct significance of this experiment.
So the option (B) is incorrect.
Its support hypothesis is that IAA is auxin that is not suitable for the significance of this experiment.
So the option (C) is incorrect.

There are many biological activities to determine the concentration of auxins harmony in the plants. The Avena coleoptile test is the first biological activity done by Dr F.W went. It is IAA ( Indole 3- acetic acid). It estimates the angle of curvature of the decollate coleoptile after placing it on an agar plate containing auxin on one side. Coleoptile tip is on the agar, agar makes bending when it is placed on the side of newly cut coleoptile stumps. This is because of the polar movement of auxin in the stem.

Hence, the correct answer is option (D).

Note: Auxins are growth promoters. It assists stem elongation, it obstructs lateral buds. Auxins are present in stem, bud, root tip. Auxins from a curving in stem tip of a plant this plant movement is called phototropism. Auxins plays an important activity in maintaining apical dominance.