Name the plant hormone responsible for elongation of cells. a. Auxin b. Gibberellin c. Abscisic acid d. Cytokinins
Hint: Plant hormones are also called as phytohormones, which are intrinsic factors that are produced in the plant for the regulation of growth and development, apart from this they also depend on external factors such as sunlight, water, etc.
Complete answer: Different types of plant hormones include > Auxins: - The term auxin meaning is to grow, which used widely in the field of agriculture and horticulture - They usually produce in the spices of roots and stems. - The main function is the elongation of the cells, apart from this they also help in cell division and differentiation of xylem. - They also help to prevent the premature fall of leaves, fruits, and flowers.
> Gibberellins: - There are so many varieties of gibberellins, and they are found in higher plants and fungi, and they are acidic in nature. - The functions of gibberellins are they promote bolting, which means useful for the sudden growth at the internodes. - It helps in the elongation of stems, and it can reverse the dwarfism and it induces parthenocarpy. - It prevents the seed dormancy and it also induces certain male characteristics in some plants.
> Cytokinins: - They are naturally produced in the plants, and useful for the cell division in the root apices, shoot buds, etc. - They help in the lateral growth of the plant, it acts and overcomes the dominance of Auxins. - It stimulates the formation of chloroplast in the leaves.
> Abscisic acid: - It is growth-inhibiting hormone, this is also called as stress hormones, it inhibits the plant metabolism - It induces the abscission of leaves, it accelerates the dormancy in seeds.
> Ethylene: - lt has dual roles such as growth promotion and growth induction. - They mainly produce in ripe fruits, they hasten the ripening and also promote senescence.
Hence, The correct answer is option (A).
Note: All hormones that are above explained are naturally produced in the plants, generally in a low concentration and they produce in one place and as an ability to act in another place.