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JAMB Biology 1983 Question 37

Question 37

Plant Responses and Hormones

In a positive phototropic response of a coleoptile, the region of greatest curvature is brought about by the

  1. A.movement of auxins away from the region of curvature
  2. B.even distribution of auxins in all parts of the coleoptile
  3. C.inhibition of growth by auxins in the region of smaller curvature
  4. D.concentration of auxins in the region of curvature
  5. E.absence of auxins in the coleoptile
Show the answer and explanation

Answer: D (concentration of auxins in the region of curvature)

Explanation

Auxin collects on the shaded side of the coleoptile, so cells there grow longer and the tip bends towards the light where the auxin is concentrated.