Question

What causes a green plant to bend towards light as it grows?

• A. Because green plants need light to carry on photosynthesis
• B. Because green plants are phototropic
• C. Light stimulates plant cells on the lighted side to grow faster
• D. Auxin accumulates on shaded side stimulating greater cell elongation

Answer 1

Answer: (D)

Auxin accumulates on shaded side stimulating greater cell elongation

Auxin is a plant hormone that plays important role in phototropism, growth movement in response to light. It promotes cell elongation. It is unequally distributed in the plant cells. It is transported towards the shady side and thus present in higher concentration. However, less auxin is transported towards the illuminated side. Due to this, the plant to grow more on the shaded side and bend in the direction of the light source. It shows phototropic response where faster cell elongation is seen on the shaded side than on the illuminated side.

Thus, the correct answer is option D.