Question

Which one us a test for gibberellin
A) Bolting of cabbage
B) Morphogenesis is tobacco callus
C)Rapid division in carrot cells
D)Elongation of oat coleoptile

Answer 1

Hint:The rosette habit of cabbage can be altered by the application of gibberellin.

Complete answer:
Gibberellins are plant hormones responsible for the regulation of various developmental processes like stem elongation, germination, dormancy, flowering, flower development, leaf and fruit senescence. Gibberellic acids or GA are one of the biggest classes of plant hormones. They are important for initiating developmental processes like seed germination .
Low concentrations can be used to increase the speed of germination and they stimulate cell elongation so that plants grow taller.
The rapid elongation of stem in rosette plants is called bolting. Either long days or cold treatment is favourable for bolting. However, bolting can be induced artificially by the application of gibberellic acid under normal conditions.
Morphogenesis is a biological phenomenon that allows cells, tissues or organisms to develop their shape.
Auxins, another plant hormone, are used for rapid cell division in carrot cultures. Auxins help in cell proliferation under controlled conditions.
Elongation of oat coleoptile under controlled conditions is also brought about by auxins. The discovery of auxin was built upon observations of phototropic bending in oat coleoptiles.

Hence the answer is option (A.) Bolting of cabbage.

Note:Actions of plant hormones are mainly deciphered under laboratory conditions by using tissue cultures.