HUMAN PHYSIOLOGY
CONTROL AND COORDINATION
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Gibberellin Gibberellin
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Etheline
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Auxin
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ABA
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Detailed explanation-1: -Auxin promotes cell elongation, causing the plant to grow more on the shady side and bend in the direction of the light source.
Detailed explanation-2: -The bending of the plant towards light is known as phototropism. It is due to the plant hormone auxins. When the growing parts of a phototropic plant detect sunlight, auxins (synthesized at the shoot tips) help the cells grow longer.
Detailed explanation-3: -When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.
Detailed explanation-4: -Under normal light conditions auxins are spread out in the plant. But when sunlight varies, auxin is broken down on the sunnier side of the stem. The higher concentration of auxin on the shady side causes the plant cells on that side to grow more so it bends toward the light.
Detailed explanation-5: -Auxin and cytokinin are critical growth hormones in plant development and are naturally present within the plant at variable concentrations throughout the season.