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Question
Assertion :The first phytohormone to be discovered was auxin. Reason: Light reaction of coleoptile tip attracted the attention of Darwin in the last quarter of nineteenth century.
Assertion :The first phytohormone to be discovered was auxin. Reason: Light reaction of coleoptile tip attracted the attention of Darwin in the last quarter of nineteenth century.
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
There are some substances produced in the plant body itself, which affects the growth of the plant called plant hormones or phytohormones or growth hormones.Auxin was the first phytohormone to be discovered. An experiment was performed by Fritz Went on oat seedling to see the effect of auxins.In 1881, Charles Darwin and Francis Darwin performed experiments on coleoptiles of canary grass and observed that they bend towards the light when exposed to light from a unidirectional source.They concluded that the tip of the coleoptile was responsible for sensing light, and proposed that a messenger is transmitted in a downward direction from the tip of the coleoptile, causing it to bend.Hence, both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. (Option B)
There are some substances produced in the plant body itself, which affects the growth of the plant called plant hormones or phytohormones or growth hormones.
Auxin was the first phytohormone to be discovered. An experiment was performed by Fritz Went on oat seedling to see the effect of auxins.
In 1881, Charles Darwin and Francis Darwin performed experiments on coleoptiles of canary grass and observed that they bend towards the light when exposed to light from a unidirectional source.They concluded that the tip of the coleoptile was responsible for sensing light, and proposed that a messenger is transmitted in a downward direction from the tip of the coleoptile, causing it to bend.
Hence, both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. (Option B)
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