Give examples of any three physiological processes that
are regulated by plant hormones
1) Phototropism: Plant hormones such as auxin regulate the growth and bending of plant stems towards a light source. Phototropism allows plants to maximize their exposure to sunlight for photosynthesis.
2) Apical dominance: Plant hormones, particularly auxin, are responsible for regulating the growth of lateral buds. The presence of auxin in the terminal bud inhibits the growth of nearby lateral buds, ensuring the upward growth of the plant.
3) Leaf senescence: Plant hormones such as ethylene regulate the process of leaf senescence, which is the natural aging and death of leaves. Ethylene promotes the breakdown of chlorophyll and other leaf pigments, leading to the yellowing and eventual shedding of the leaves.
1. Phototropism: Phototropism is the process by which plants bend or grow towards a light source. It is regulated by the plant hormone called auxin. When light is detected by the plant, auxin accumulates on the shaded side of the stem. This causes the cells on the shaded side to elongate, resulting in the bending of the stem towards the light source.
2. Apical dominance: Apical dominance refers to the phenomenon where the growth of lateral buds is inhibited by the presence of an actively growing apical bud (located at the tip of the stem). This process is regulated by the plant hormone called cytokinin. Cytokinin promotes the growth of lateral buds and counteracts the inhibitory effect of auxin produced in the apical bud, allowing the lateral buds to grow.
3. Abscission: Abscission is the process by which plants shed or drop their leaves, flowers, or fruits. It is regulated by the plant hormone called ethylene. When a plant signals the need to shed a particular organ, such as a leaf, it produces ethylene, which triggers the breakdown of the cells in the abscission zone (a specialized area at the base of the leaf or fruit stem). This results in the separation and eventual shedding of the organ.