Growth of the stem is controlled bya)Gibberellinb)Auxinc)Abscisic acid...
Auxins
Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than corresponding cells on the lighter side of the plant. This produces a curving of the plant stem tip toward the light, a plant movement known as phototropism.
Auxin also plays a role in maintaining apical dominance. Most plants have lateral (sometimes called axillary) buds located at nodes (where leaves attach to the stem). Buds are embryonic meristems maintained in a dormant state. Auxin maintains this dormancy. As long as sufficient auxin is produced by the apical meristem, the lateral buds remain dormant. If the apex of the shoot is removed (by a browsing animal or a scientist), the auxin is no longer produced. This will cause the lateral buds to break their dormancy and begin to grow. In effect, the plant becomes bushier. When a gardener trims a hedge, they are applying apical dominance.
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Growth of the stem is controlled bya)Gibberellinb)Auxinc)Abscisic acid...
Control of Stem Growth by Auxin
The growth of the stem is controlled by a hormone called Auxin. Auxin is a plant hormone that regulates cell elongation and division in the stem. The following are the ways in which Auxin controls the growth of the stem:
1. Cell Elongation: Auxin promotes the elongation of cells in the stem. The hormone increases the plasticity of the cell wall, which allows the cells to stretch and elongate. This results in the growth of the stem.
2. Apical Dominance: The apical bud of the stem produces more Auxin than the lateral buds. This results in the inhibition of the growth of the lateral buds. The apical bud continues to grow, while the lateral buds remain dormant.
3. Phototropism: Auxin is responsible for the plant's response to light. When light shines on one side of the stem, Auxin moves to the shaded side of the stem. This results in the elongation of the cells on the shaded side, which causes the stem to bend towards the light.
4. Gravitropism: Auxin is also responsible for the plant's response to gravity. When a plant is placed horizontally, more Auxin accumulates on the lower side of the stem. This results in the elongation of the cells on the lower side, which causes the stem to bend upwards.
Conclusion
In conclusion, Auxin is the hormone responsible for the growth and development of the stem. The hormone controls cell elongation, apical dominance, phototropism, and gravitropism in the stem.
Growth of the stem is controlled bya)Gibberellinb)Auxinc)Abscisic acid...
Auxins promote cell enlargement and cell differentiation in plants leading to growth. They are produced by cells at the tip of stem and roots. They can also drastically affect plant orientation by promoting cell division in one side of the plant in response to sunlight and gravity.
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