THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -Unequal distribution of auxin causes bending of shoots towards sunlight. Auxin is a hormone synthesized by meristematic cells at shoot tip. It moves from shoot tip to other parts and tends to get accumulated more on the darher side of the plant.

Detailed explanation-2: -No, you do not find the same amount of auxin in all the tissues of a plant. In fact, the uneven auxin distribution is a key factor for proper development. IAA concentrations can differ by an order of magnitude between shoot and root and appear highest in meristems located at the tip of the roots and the shoots.

Detailed explanation-3: -Light imposes a high degree of control on auxin levels and distribution but its action is not restricted to these processes; light also moderates the sensitivity to auxin within the cell. By imposing control on the nuclear auxin response pathway, light can dampen or amplify the response to auxin.

Detailed explanation-4: -Phototropism: Unequal distribution of auxin causes phototropism. It causes the plant growth either away or towards the light, based on which part receives light. Auxins are present in higher quantities on the shaded side of a stem. Since auxins promote stem elongation, the shaded part grows taller.