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Post-UTME Biology 2019 Objective — Question 5

Question 5 of 20 from the Post-UTME Screening (Post-UTME) Biology 2019 Objective paper, with the correct answer and a full explanation.

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The tip of a maize coleoptile bends towards one-sided illumination because the growth hormone is

  • A. more concentrated on the dark sideCorrect
  • B. more concentrated on the illuminated side
  • C. evenly distributed on both sides
  • D. completely absent from the illuminated side

Explanation

Auxin migrates to the shaded side of the coleoptile, stimulating greater cell elongation there, which causes the tip to bend towards the light (positive phototropism).

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