Question

A plant hormone which delays senescence and helps in cell division is _____
A. Auxin
B. Gibberellins
C. Cytokinin
D. Abscisic acid

Answer 1

Plant hormones play a very important role in the development of plants. Senescence is the process in which leaves of the tree shed down. Auxin helps in growth and development of the plant. Cytokinin stimulates the proteins needed for mitosis. Kinetin is the main compound to promote cell differentiation in plant parts.

Complete answer:
Cytokinins are the plant growth hormones also called as phytohormones that promote cell division in roots and shoots. Cell division can also be termed as cytokinesis that’s why they are named as cytokinins. The major function of cytokinins is cell differentiation but they also show effects on apical dominance, axillary bud growth, and leaf senescence. Cytokinins can be adenine type or phenylurea type. Only adenine type cytokinins are found in plants. Auxin and cytokinin together show greater effects on development of plant parts. If only auxin is present then parenchyma cells grow large but do not divide when cytokinin is added cells expand and differentiate.
Cytokinins also help to delay ageing process of plant organs. They prevent protein breakdown and activate protein synthesis and also collect nutrients from surrounding tissues. Scientists that were regulating the leaf senescence process in tobacco plants observe that wild type leaves turn yellow while transgenic leaves remain green. From this it is said that cytokinin regulates protein synthesis and degradation. The principle compound which induces cell division was isolated from yeast and called as kinetin, it is later termed as cytokinin.
Gibberellins help in seed germination, stem elongation, leaf expansion, and pollen maturation etc. while the abscisic acid is an inhibitory hormone which promotes dormancy in seed.
From the above information we can say that cytokinin is the plant hormone which delays senescence and helps in cell division.

So, the correct answer is option C.

Note: Cytokinins are used by farmers to increase crop yield. Now, cytokinin also found a role in plant pathogens. Auxin promotes cell elongation and also moves to the darker side of the plant to promote larger cell growth in that region. Gibberellins are present in the plant cell plastids or membrane bound organelles responsible for food making. Abscisic acid is also known as stress hormone.