Q28 / 180 · NEET 2015 (Phase 1) · Botany

What causes a green plant exposed to the light on only one side, to bend toward the source of light as it grows?

  • A
    Green plants need light to perform photosynthesis.
  • B
    Green plants seek light because they are phototropic.
  • C
    Light stimulates plant cells on the lighted side to grow faster.
  • Correct answer
    D
    Auxin accumulates on the shaded side, stimulating greater cell elongation there.

Solution

Auxins accumulates on the shaded side, stimulating grater cell elongation there. Since auxins move from morphological apex to morphological base therefore gets accumulated on the shaded side. Thus plants exposed to the light on only one side bends towards the source of light. It is also due to the tropic movement of auxins which causes phototropism and geotropism in plants.

Hence, the correct answer is option: 'D'.

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