Question

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

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

Answer 1

The correct option is D inhibited, promoted

Shedding of mature leaves from the stem or ripe fruits 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 the distal side and less auxin on the proximal side. The abscission zone formation occurs rapidly when the auxin gradient becomes slight or neutral. Moreover, the plant hormone ethylene is found to promote the abscission. Thus, a high concentration ocean prevents the formation of abscission layer and the phenomenon is controlled by the concentrations of auxin and ethylene. Apical dominance is promoted by auxin.

So the correct answer is "inhibited, promoted".