AP BIOLOGY

Detailed explanation-1: -Detailed Solution. The Plant hormone Auxin causes the plant to bend towards the sunlight. It is a growth stimulant in plants. Auxin is broken down on the sunnier side of the plant.

Detailed explanation-2: -Under normal light conditions auxins are spread out in the plant. But when sunlight varies, auxin is broken down on the sunnier side of the stem. 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.

Detailed explanation-3: -Auxin is a key regulator of plant growth and development, orchestrating cell division, elongation and differentiation, embryonic development, root and stem tropisms, apical dominance, and transition to flowering.

Detailed explanation-4: -The bending of the plant towards light is known as phototropism. It is due to the plant hormone auxins. When the growing parts of a phototropic plant detect sunlight, auxins (synthesized at the shoot tips) help the cells grow longer.

Detailed explanation-5: -The hormones responsible for phototropism are auxins. Bending of the plant is caused by more elongation of the shaded part as compared to the lighter side, caused by increased auxin concentration on shaded side and decreased on the other side.