Plant Growth and Development Question 21
21. 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? [2014]
(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 movement of auxins.
Show Answer
Answer : b
Hints & Solutions
(b) Charles Darwin and his son Francis Darwin observed that the coleoptiles of Oat (Avena sativa) and canary grass (Phalaris canariensis) responded to unilateral illumination by growing towards the light source (phototropic curvature or phototropism). After a series of experiments, it was concluded that the tip of the coleoptile was the site of production of a substance, that caused the bending of coleoptile.
