25-1 Hormones and Plant Growth. Essential Question How do hormones affect plant growth and development?. Patterns of Plant Growth. Plants follow general patterns of growth that differs among species.
How do hormones affect plant growth and development?
Auxins the same hormone causing it to behave in different ways are hormones that stimulate cell elongation.
They are produced in the apical meristem and transported downward into the rest of the plant.
When light hits one side of a stem,
a higher concentration of auxins
develops in the shaded part of the stem causing cells on the shaded side to elongate
As a result, the stem bend away from the shade and toward the light.
Phototropism is the tendency of a plant to grow towards the source of light.Auxins and Phototropism
Opaque shiedover base
divisions in meristems such
as lateral buds.
area on the side of a stem that
gives rise to side branches.
bud is regulated by auxins
Auxins produced in the apical meristeminhibit the growth of lateral buds.
Apical meristem removed
Without the inhibiting effect of auxinsfrom the apical meristem, lateral budsproduce many branches.
that are toxic to plants.
that mimic the effects of auxin by inhibiting growth.