auxins are not stable in light because it will degenerate the hormones.so,when light touches at one side of the coleoptile,auxins will move to the other side (less sunlight).this makes the shoot grow faster at the side which have more auxins and slower at the place where there are less auxins and this makes the shoot bend towards the light source =P
Auxin's cause plants to respond positively to sunlight. Auxin's were the first major plant hormone to be discovered. Auxin's, produced in the meristems of plants, are responsible in promoting cell elongation.
It is Auxin
auxin
this is called a tropism, where the growth of a plant in a particular stimulus, (light in this case). A chemical called auxin causes the elongation of cells. When a shoot is illuminated from one side, auxin is transported down the shaded side. This shaded side then elongates more rapidly than the illuminated side, causing the shoot to bend towards the light. Also the stimulus(light) must be detected by the tip of the plant shoot or root.
auxin
yes
No, the auxin produced on the side facing the light source simply moves to the side away from the light. This causes cell elongation on the side opposite the light, making the stem appear to "grow toward the light"
light , the direction of light, they are bound to move in the direction where the light came from.
Auxin accumulates on the lower surface of the root and inhibits elongation of cells in that region.
Auxin moves away from the light to the shady side
Plants have a hormone called auxin in them. When a plant is exposed to light and shade this hormone(auxin) reacts. For example: If light falls on the right hand side of the plant, the left hand side would be in the shade. This makes the auxin expand in the shaded area, causing the plant to grow towards the light.
Auxin
When concluded that auxin accumulated on the side of the plant away from the light. When auxin flowed in this direction, the cells of the apical meristem elongated on that side and caused the plant to bend toward the light as growth continued.
Greater concentration of auxin in the cells facing light restrict cell elongation whereas on the other side (away from light) more elongation of cells takes place due to optimum amount of auxin. thus, the shoots turn towards light.
Auxin
A growth hormone called auxin.
Phototropism is the response to light. It is achieved by the action of the hormone auxin. Auxin is made in the apical meristems, moves downward by active transport into the sone of elongation and generates grow by stimulating elongation. When all sides of the apical meristem are equally illuminated, growth of the stem is uniform and the stem grows straight. When the stem is unequally illuminated, auxin moves downward into the zone of elongation but concentrates on the shady side of the stem. Auxin that would have normally accumulated on the sunny side end up on the shady side. The higher the concentration of auxin in the shady side of the stem causes differential growth. Since auxin generates growth by stimulating elongation, the shady side grows more than the sunny side. When the shady side grows more than the sunny side, the stem would bend towards the light.