BIOLOGY
HORMONES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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one whose tip is covered with a black plastic cap
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one whose tip is separated from its base by aluminum foil
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one whose tip is separated from its base by a gelatin block
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one whose tip is cut off
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Detailed explanation-1: -Phototropism is a directional response that allows plants to grow towards, or in some cases away from, a source of light.
Detailed explanation-2: -Auxin is the hormone that causes bending of the plant towards light. Auxin synthesized by the cells present in area receiving light moves towards the shady side of the stem and causes elongation of that part. Thus the shoot appears bent towards light.
Detailed explanation-3: -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-4: -When light falls on the plant, auxin moves to the darker side of the plant(Shaded region). It causes the cells in that region(darker side) to grow larger than the cells corresponding to the lighter side of the plant. This causes the plant to bend towards the source of light.