Question

Which of the following is a plant hormone?
A) Insulin
B) Thyroxin
C) Oestrogen
D) Cytokinins

Answer 1

Hint:Like humans, the plants also secrete different hormones that affect their growth and development and also the cell function. The plants do not have glands like humans; they release hormones as the secondary metabolites that are produced during the metabolic reactions.

Complete answer:
To answer this question, we have to first know about plant growth hormone. For the growth of a plant many hormones function together. The plants secrete hormones like; auxin, gibberellins, ethylene, cytokinins, brassinosteroids, salicylic acid, jasmonates, and strigolactones. Some of the hormones like abscisic acid affect the plant growth by increasing dormancy of seeds by cell inhibition. Auxin and cytokine are the major growth hormones of the plants, they involve in the growth regulation in plants. In the presence of auxin and cytokinins cell elongation in roots and shoots takes place. Auxin promotes the growth towards the gravity away from the light and cytokinins promote the growth towards the light. It also plays an important role in the cell division process, development of fruits, inhibiting lateral branching, and leaf fall. As we have understood that auxin promotes the growth towards light against geotropism, therefore we assume that it moves from apical to basal end, that is its movement is largely basipetal. On the other hand, gibberellins promote the elongation of cells in seedlings; it also affects the cell cycle of the plant.
Now, from the above discussion we can conclude that cytokinin is the plant hormone among the other given hormones. The insulin, thyroxine, and oestrogen are hormones secreted in animals and humans. The insulin is the hormone that controls the blood sugar level inside the body, thyroxine is the hormone secreted by thyroid glands, and oestrogen is the hormone secreted by the ovary involved in the reproduction process.

Hence, the correct option is ‘D’. Cytokinins.

Note: The abscisic acid affects the growth of the seed coat including the thickness, and also affects the gibberellin-mediated embryo growth. This hormone can also mediate the endosperm dormancy, therefore this hormone is used artificially for the conservation of seeds.