IMMUNOLOGY

Detailed explanation-1: -As per evidence, gibberellins enhances stem-growth especially when put on to the whole plant. These are also responsible for elongation of rosette plants such as lettuce upon exposure to some environmental stimuli, for instance, long periods of exposure to daylight.

Detailed explanation-2: -Generally, the bolting (stem elongation from rosette plants) of winter annuals is believed to be induced by an increase in the levels of gibberellin that occurs after a certain period of chilling (vernalization), and a deficiency of gibberellin allows the plant to maintain a rosette style.

Detailed explanation-3: -Like auxins, gibberellins generally increase the rate of cell division and longitudinal cell expansion. Gibberellins also exert their effects by altering gene transcription through a mechanism similar to auxin in that a pathway is turned on by inhibiting the inhibitor of that pathway (a double-negative is a positive).