Answer: Auxin accumulates on the lower side of the roots and inhibits the elongation of cells in that region.
Explanation:
Auxin is a type of growth hormone that helps in the growth and development of the plant.
When a stem is placed horizontally, then the bottom part of the plants contains more auxin and it grows more.
The auxin accumulates on the lower side of the roots and inhibits the elongation of cells in that region.
