MP Board · Class 10 · Science · Control and CoordinationWhat are plant hormones? Name four major types of plant hormones and state one main function of each.

Plant hormones, also known as phytohormones, are naturally occurring organic chemical substances produced in plants that coordinate growth, development, and responses to environmental stimuli. Unlike animals, plants do not possess a nervous system, so they rely entirely on these chemical messengers for internal coordination. Four major types of plant hormones and their main functions are: 1. Auxin: It promotes cell elongation, stem growth, and plays a vital role in phototropic responses by accumulating on the shaded side of the stem. 2. Gibberellin: It stimulates stem elongation, seed germination, and overall vegetative growth in plants. 3. Cytokinin: It promotes rapid cell division, particularly in areas of rapid growth like fruits and seeds, and delays the aging of leaves. 4. Abscisic Acid: It acts as a growth inhibitor, promoting processes like wilting and falling of leaves (abscission) and inducing seed dormancy during unfavorable environmental conditions.