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

Explanation

The phenomenon described in the question is known as phototropism, which is the growth or bending of a plant in response to light. When a green plant is exposed to light on only one side, the plant hormone auxin plays a crucial role in causing the bending towards the light source. Here's how it works:Light stimulates the plant cells on the lighted side: When light falls on one side of the plant, it stimulates the cells on that side.Auxin accumulation on the shaded side: Auxin is a plant hormone that is typically produced in the growing tips of shoots and is involved in regulating plant growth and development. In response to light, auxin accumulates on the shaded side of the plant.Unequal distribution of auxin causes differential growth: The accumulation of auxin on the shaded side creates an unequal distribution of auxin between the lighted and shaded sides of the plant. This unequal distribution of auxin leads to differential growth between the two sides.Greater cell elongation on the shaded side: The side with higher auxin concentration (shaded side) experiences enhanced cell elongation compared to the side with lower auxin concentration (lighted side). As a result, the plant bends towards the light source.Option B correctly explains this process by stating that auxin accumulates on the shaded side, stimulating greater cell elongation there, causing the plant to bend towards the light. The other options (A, C, and D) are not directly related to the specific mechanism of phototropism and do not explain the bending of the plant towards the light source.