NEET 2015 Biology question

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

(1)Green plants seek light because they are phototropic
(2)Light stimulates plant cells on the lighted side to grow faster
(3)Auxin accumulates on the shaded side, stimulating greater cell elongation there.Correct
(4)Green plants need light to perform photosynthesis

Answer: (3)

Solution

In phototropism, unilateral light causes the auxin (IAA) to move laterally from the illuminated side to the shaded side of the shoot. The higher auxin concentration on the shaded side stimulates greater cell elongation there, so the shoot bends towards the light. Option (1) just restates the

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Question ID VK-091740