Removal of auxin source demonstrates that leaf abscission is _______by auxin, and apical dominance is________by auxin.

Options

A. promoted, promoted
B. inhibited, inhibited
C. promoted, inhibited
D. inhibited, promoted

Answer

D

Explanation

Shedding of mature leaves from the stem or ripe furits from the stem is called abscission. Generally a layer of tissue is formed at the base of the organ. This layer of tissue is called abscission zone. Abscission zone does not occur when the concentration of auxin is high, particularly when the gradient of auxin is steep, i.e, more auxin on distal side and less auxin on proximal side. the abscission zone formation occus rapidly when the auxin gradient become slight or netural. Moreover, the plant hormone ethylene is found to promote the abscission. Thus, a high concentration of auxin prevents the formation of abscission layer and the phenomenon is controlled by the concentrations of auxin and ethylene. Apical dominance is promoted by auxin.