Name a plant hormone that can never act alone. List any three activities of this hormone in conjunction with auxins.

Hint: Plant hormones are chemical substances that help in the growth and development of plants. It performs various important physiological processes in plants such as cell division, elongation, germination, cytokinesis etc.

Complete step by step answer: Cytokinins are plant growth-regulating hormones that cannot act alone to produce effects on plants. They have specific effects on the process of cytokinesis. Zeatin was the first cytokinin that was discovered. After the discovery of zeatin, many other natural cytokinins were discovered. Some synthetic compounds have cell division promoting activity. Natural cytokinins are synthesized in regions having active cell division. They are commonly produced in root apices, young fruits, developing shoot buds, etc. Most of the phytohormones regulate various activities. Cytokinins regulate plant processes in conjunction with auxins or indole acetic acid (IAA). Cytokinins regulate various processes that are as follows:
a. They help in the production of new leaves.
b. They increase the number of chloroplasts in leaves.
c. They induce lateral root growth and adventitious shoot formation.
d. They help to overcome leaf dominance.
e. They also promote nutrient mobilization that helps to delay leaf senescence.

Note: Auxins are plant growth regulators that can be natural and synthetic and have certain growth-regulating properties. Auxin is also known as Indole-3-acetic acid and is commonly produced by the growing apices of the stems and roots. But high concentrations of auxin can inhibit root elongation and stimulate adventitious root elongation. Secondary root formation can be inhibited by the removal of root tips.