BIOLOGY
HORMONES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Auxin is destroyed by light.
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Gibberellins are destroyed by light.
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Auxin synthesis is stimulated in the dark.
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Auxin moves away from the light to the shady side.
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Detailed explanation-1: -When light hits one side of the coleoptile, the phototropins are more active on the side with light, causing the auxin to flow down the shady side. The side of the coleoptile with less auxin has less elongated cells, and the side with more auxin has more elongated cells, causing the tip to bend toward the light.
Detailed explanation-2: -It grows because the auxin causes the cells to elongate on the shaded side, so this side grows more. This unequal growth of the two sides, results in the growth of the stem towards the light.
Detailed explanation-3: -Auxins have the opposite effect in roots. This is negative phototropism. In a root the shaded side contains more auxin but grows less. This causes the root to bend away from the light.
Detailed explanation-4: -Light imposes a high degree of control on auxin levels and distribution but its action is not restricted to these processes; light also moderates the sensitivity to auxin within the cell. By imposing control on the nuclear auxin response pathway, light can dampen or amplify the response to auxin.
Detailed explanation-5: -In whichever direction the hetero-auxin is transported in coleoptiles, it accelerates their growth. 4. In decapitated dark-grown sunflower hypocotyls also the same paste applied to one side near the base causes negative curvatures above within 24 hours, indicating acceleration of growth.