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Plant Growth

Auxins, primarily produced in the tips of shoots and roots, play a critical role in plant growth by regulating the elongation of cells. They influence how plants respond to light and gravity, a phenomenon known as phototropism and geotropism, respectively. In phototropism, light causes auxin concentration to be higher on the shaded side of a shoot, encouraging it to bend toward the light. In geotropism, auxins cause differential growth in roots and shoots when placed horizontally, directing roots downwards and shoots upwards, thus allowing plants to orient themselves according to gravitational pull.

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Plant Growth

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  1. Plant Growth Auxins Phototropism Geotropism By Jay and Toby

  2. Auxins • Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the plant • Auxins change the rate of elongation in plant cells, controlling how long they become • Shoots and roots respond differently to high concentrations of Auxins • cells in shoots grow more • cells in roots grow less.

  3. Phototropism • In a shoot, the shaded side contains more auxin • This means that the shaded side grows longer, causing the shoot to bend towards the light • The diagram shows the typical results seen when growing oat seedlings in a box, with a light at one side.

  4. Geotropism • Auxins are also involved geotropisms • In a root placed horizontally, the bottom side contains more Auxins than the top side • This makes the bottom side grow less than the top side, causing the root to bend in the direction of the force of gravity. • In a shoot placed horizontally, the bottom side contains more auxinsthan the top side • This makes the bottom side grow more than the top side, causing the shoot to bend and grow against the force of gravity

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