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Biology · Plant Growth and Development
हिन्दीCharles Darwin and his son Francis Darwin conducted experiments on canary grass coleoptiles and deduced that phototropic curvature was due to a transmissible influence. Which observation led directly to this deduction?
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Correct answer · Option C
Unilateral illumination caused bending only when the coleoptile tip was intact or uncovered, but bending ceased when the tip was removed or covered with an opaque cap
Explanation
Darwins observed that intact coleoptiles bent toward unilateral light, but decapitated or opaque-cap-covered coleoptiles did not, demonstrating that the tip was the site of transmissible influence.
