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 quantitative determination of small amounts of growth- promoting substances.
• C. It supports the hypothesis that IAA is auxin.
• D. It demonstrated polar movements of auxins.

Answer 1

The correct option is B It is the basis for quantitative determination of small amounts of growth- promoting substances.

Answer is option B i.e. "It is the basis for quantitative determination of small amounts of growth- promoting substances."
Dr F. Went isolated Auxin from Avena coleoptile tip. His experiment demonstrated the polar movement of auxins. Tryptophan is the precursor of Indole acetic acid (IAA, natural auxin). Important biassay of auxins are Avena curvature test and cross root inhibition test.