Plant responses
Tropisms
● Directional growth to a stimulus .
○ Phototropism
○ Geotropism
○ Hydrotropism
○ Chemotropism
○ Thigmotropism
PHOTOTROPISM
● Positive: shoot towards light source
● Negative: root towards soil with minerals and water
AUXIN
On shaded side
Stimulates growth in shoots and cell elongation = shoot bends towards light source
Stimulate active transport of H+ via ATPase into cell walls
Lowering pH : optimum for expansins which hydrolyse bonds in cellulose and weakens
them.
Tropisms
● Directional growth to a stimulus .
○ Phototropism
○ Geotropism
○ Hydrotropism
○ Chemotropism
○ Thigmotropism
PHOTOTROPISM
● Positive: shoot towards light source
● Negative: root towards soil with minerals and water
AUXIN
On shaded side
Stimulates growth in shoots and cell elongation = shoot bends towards light source
Stimulate active transport of H+ via ATPase into cell walls
Lowering pH : optimum for expansins which hydrolyse bonds in cellulose and weakens
them.
