Question

You studied many plant hormones in class, why do you think it is important to study and understand plant hormones. Give reasons and examples of why plant hormones are important .

Answer 1

Answer:

To study the plant hormones or chemical messangers is important because it mainly plays an important role in growth of plants. These plant hormones acts as signal molecules and regulate function of cellular processes in targeting cells. They also estimate root, stem, flower, leaf, shedding of leaves, development and ripen of fruits.

As in the humanbeings, number of hormones is present to function and regulate various metabolic pathways and development of body parts , hair, nails, reproductive organs to achieve puberty various hormones play an important role same like that plants hormones also play an important role in growth, stem elongation, development of leaf, flower etc.

These are the main important roles of 5 plant hormones which mainly influences germination, growth, elongation, metabolism, ripening and other physiological activities of the entire plants.

There are 5 types of plant hormones:

1. Auxin : It is indole - 3 - acetic acid (IAA), which is responsible for cell expansion and growth. The auxin is present in top of the plant in higher concentration and decreases concentration while reaching to the roots. It involves in the bending of the plant, auxin is moved to the shaded side of the plant and stem elongation occurs more on shaded side than the sunny side. The sunny side plant remains same size, therefore bending of the plant occurs.

2. Gibberellins: It is same as auxin functions. It mainly involves in growth of rice plants because the fungus called Gibberella fujikuroi causes stimulation of too much growth in the rice plants which makes plant taller and allows falling down. Gibberellins: Although it is having same function as auxin, Gibberellins mainly promote stem elongation between nodes on the stem and internodes elongation. Gibberellins are not seen in dwarf plants and rosette plants due to its less space.

3. Cytokinin: It is named after kinetin. Cytokinins are mainly responsible for cell division, self repair - if any part of the plant is damaged, immediately auxin and Cytokinin repair that part of plant. It also delays natural aging of the plants. This Cytokinins present mostly in young plants. This promotes movement from G2 phase to the M phase. There by it promotes cells to divide.

4. Ethylene: It mainly involves in ripening fruits. Example: Mangos, tomatoes and bananas, etc., are ripening in presence of ethylene gas. The formation of ethylene gas requires oxygen. The slowing down process can also made in presence of partial pressure with low oxygen and high carbon-dioxide.\

5. Abscisic acid: The main role of abscisic acid is giving signals during dehydration of the plants (means droughted seeds, roots, stem etc) and makes the entire plant hydration during raining. This happens by leaving water from the leaves if excess is present in guard cells (i.e by stomata which is present like pores in a leaf) .The excess water will flows down from to bottom and reaches into soil. Each stoma has two guard cells loaded with water and helps in alerting the stoma. During the water scarce conditions, abscisic acid gives signals to the guard cells that then automatically guards cells alert to the stomata by shriveling and immediately closes the stoma.

Auxin: stem elongation, fruit development, leaf abscission.

gibberellins: stem elongation, leaf abscission. seed & stem growth fruit development, break winter dorminancy.

cytokinin: cell division and auxillary bud growth.

Ethylene: ripenening of fruits and inhibits stem elongation.

abscisic acid: maintains seed & winter dorminancy and stomata closes.

Note: The provided answer is as per my knowledge may be or may not be 100% correct, but definitely relevant to your question thank you so much.