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Which of the following plant hormones promotes cell division?
(a)Auxin
(b)Cytokinin
(c)Ethylene
(d)Gibberellin

Answer
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Hint: The hormone which will stimulate both differentiation and therefore the outgrowth of axillary buds. This hormone will also affect apical dominance, axillary bud growth, and leaf senescence.

Complete answer:
Cytokinin (CK) is a category of plant growth substances ( also called phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. These hormones are responsible for cell proliferation and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.

Additional Information:
Cytokinin is the hormone that is vital for cell proliferation and differentiation.
It's known that cytokinin plays a key role in many aspects of plant growth and development; including embryogenesis, maintenance of roots and shoot meristems, etc.
Functions of cytokinin are:
- cell division.
-Root and shoot meristems.
-Cell differentiation
-Leaf senescence
-Inflorescence growth.
-Nutrient mobilization.
-cotyledon expansion.
-Apical dominance
-Seedling morphology.
The ratio of auxin to cytokinin:
The ratio of auxin to cytokinin plays a crucial role within the effect of cytokinin on plant growth and Cytokinin alone does not affect parenchyma cells.
-When cultured with auxin but no cytokinin, they grow large but don't divide.
-The cells expand and differentiate by the addition of cytokinin.
- The parenchyma cells form an undifferentiated callus by the addition of auxin and cytokinin equally.
- Addition of more cytokinin induces growth of shoot buds, while more auxin induces root formation.

So, the correct answer is, ‘‘Cytokinin’’.

Note: -The chemical name of cytokinin is zeatin (chemical name: 6-(4- hydroxy-3-methyl but-2-enyl amine)purine.
-Cytokinin is the hormone that is vital for cell proliferation and differentiation.
-Cytokinin is produced in the root apical meristems and travels upward with water and travels up the stem through the xylem.