This category covers three important plant growth regulators: cytokinins, which promote cell division and delay aging; ethylene, which regulates fruit ripening and senescence; and abscisic acid, which helps plants respond to stress and dormancy. It includes explanations and practice questions to clarify their functions.
Heterophylly, the presence of different leaf types in the same plant (e.g., coriander), is an example of developmental plasticity.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Ethylene promotes flowering in mango and is widely used to synchronize fruit set.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Cytokinins are produced in root tips and promote cell division and shoot growth. They delay, not promote, leaf senescence.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Ethylene promotes, not inhibits, flower senescence. It is also known for fruit ripening and promoting abscission.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Cytokinins primarily promote shoot growth, not root growth. They delay senescence and promote cell division.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Lateral meristems, such as vascular cambium and cork cambium, contribute to secondary growth, increasing girth.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Abscisic acid induces seed dormancy, helping seeds survive unfavorable conditions. Cytokinins promote, not inhibit, cell division, and ethylene promotes, not delays, fruit ripening.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Cytokinins delay senescence (aging) and promote cell division, making them essential for shoot formation in tissue culture.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Ethylene induces apical hook formation in dicot seedlings to protect the shoot tip during germination.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Cytokinin was discovered by F. Skoog and co-workers during experiments on tobacco stem callus proliferation.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Cytokinins delay, not promote, leaf abscission. Ethylene promotes abscission and senescence.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
Abscisic acid (ABA) is called the stress hormone as it helps plants respond to drought by closing stomata and inducing dormancy.
Ref: NCERT Class 11 Biology Chapter 13: Plant Growth and Development Plant Growth Regulators - Cytokinins Ethylene and Abscisic Acid
