HORTICULTURE

Detailed explanation-1: -The higher concentration of auxin on the shady side causes the plant cells on that side to grow more so it bends toward the light. Because light is the energy source for plant growth, plants have evolved highly sensitive mechanisms for perceiving light.

Detailed explanation-2: -In a stem, the shaded side contains more auxin and grows longer, which causes the stem to grow towards the light. The plant does NOT bend towards the light. It grows because the auxin causes the cells to elongate on the shaded side, so this side grows more.

Detailed explanation-3: -When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.

Detailed explanation-4: -Auxin stimulates cell elongation on the shady side of the stem through a process called the acid growth hypothesis: Auxin causes cells to activate proton pumps, which then pump protons out of the cells and into the space between the plasma membrane and the cell wall.

Detailed explanation-5: -The plant hormone auxin is well known to stimulate cell elongation via increasing wall extensibility. Auxin participates in the regulation of cell wall properties by inducing wall loosening.