MCQ
Q.
The hormone responsible for ripening of fruits is
Correct Answer: A
Concept:
- Plant growth hormones or phytohormones are simple molecules with complex chemical composition, that regulates the growth and physiology of plants.
- Based on their functions on the living plant body they can be classified into two groups:
- Plant growth promoters - Promotes activities like cell division, cell enlargement, flowering, fruiting, etc. Eg. Auxins, Gibberellins & cytokinins.
- Plant growth inhibitors - They are involved in various growth-inhibiting activities like dormancy, and abscission. Eg. Abscisic acid.
- Gaseous PGR like ethylene can be put into both groups, however, it is largely an inhibitor of growth activities.
Explanation:
- Ethylene is a simple gaseous PGR.
- It is synthesized in large amounts by tissues undergoing senescence and ripening fruits.
- Influences of ethylene on plants include horizontal growth of seedlings, swelling of the axis, and apical hook formation in dicot seedlings.
- Ethylene promotes senescence and abscission of plant organs, especially of leaves and flowers.
- Ethylene is highly effective in fruit ripening. It enhances the respiration rate during the ripening of the fruits. This rise in the rate of respiration is called respiratory climactic.
- Ethylene breaks seed and bud dormancy, initiates germination in peanut seeds, sprouting of potato tubers.
- Ethylene promotes rapid internode/petiole elongation in deepwater rice plants.
- It helps leaves/ upper parts of the shoot to remain above water.
- Ethylene also promotes root growth and root hair formation, thus helping the plants to increase their absorption surface.
Additional Information
| Plant hormone | Effects |
| Cytokinin |
|
| Auxin |
|
| Abscisic Acid (ABA) |
|
