Biology 2016 JAMB Past Questions - Question 4: Which of the following plant hormone is responsible for ripening of fruits?

Correct Answer

C

Explanation

Ethylene (old nomenclature ethylene) gas. if unripe fruits such as oranges or mangoes are enclosed in an air tight container such as basket with water proof lining the inside the fruits ripe faster than when on the plant. The epicarp of unnpe fruits secretes ethene which in high concentration forces all the fruits to ripe at the same time. Abscisic acid promotes leaf and fruit fall by formation of abscission zone at the base of leaf petiole and fruit stalk in which the xylem and phloem are blocked preventing the supply of mineral salts to these parts and conduction of manufactured food. These parts become weak and fall at the slightest wind. Gibberellin - This hormone together with auxin promote/stimulate growth - plants. They make cells to divide repeatedly, elongate and differentiate. Cytokinin - Promotes the growth of the lateral buds inhibited by apical dcm ~3r,ce. !t also breaks seed dormant i.e makes seeds to germinate.