I: | It is synthesised in large amounts by tissues undergoing senescence and ripening fruits. |
II: | It promotes senescence and abscission of plant organs especially of leaves and flowers. |
III: | It enhances the respiration rate during ripening of the fruits. |
I: | Auxins, gibberellins and cytokinins are plant growth promoters. |
II: | ABA is an inhibitor of plant growth activities. |
III: | Ethylene is largely a plant growth promoter. |
1. | Gibberellin | 2. | Ethylene |
3. | Cytokinin | 4. | Auxin |
PGR | Chemical nature | Discovered by | |
1. | Auxin | Indole | F. W. Went |
2. | Gibberellin | Sphingosines | Yoshinori Ohsumi |
3. | Cytokinin | Adenine derivatives | Skoog and Miller |
4. | Ethylene | Gaseous | Cousins |
1. | It breaks seed and bud dormancy |
2. | It initiates germination in peanut seeds |
3. | It does not allow sprouting of potato tubers |
4. | It promotes root growth and root hair formation. |
1. | IAA | 2. | Ethylene |
3. | Gibberellin | 4. | Cytokinin |
1. | Plant roots are extensible |
2. | Plants do not respond to environmental condition around them |
3. | Stems can extend |
4. | Plants have the ability to produce different phenotypes in response to environmental changes |
1. | Differentiation | 2. | De-differentiation |
3. | Re-differentiation | 4. | Anti-differentiation |
1. | Only I | 2. | Only II |
3. | Both I and II | 4. | Neither I nor II |