Homeostasis: Plant Hormones Flashcards
Auxin, Tropism,
What is a hormone?
> Chemical messenger secreted from glands
> Carried in bloodstream
> Alter activity in specific target organs
What do hormones help plants do?
Respond to changes in environment
Types of changes to environement?
> Light
> Water
> Gravity
What are an auxin?
Growth hormone
> Cause cell ELONGATION
What do auxin do?
> Coordinates response
> Controls plant growth
What are tropisms/tropic responses?
Directional growth response causing MOVEMENT
What is Phototropism?
Response to light
What is Hydrotropism?
Response to water
What is Gravitropism?
Response to gravity
What is Negative Tropism?
Growth AWAY from stimuli
What happens at Roots?
Tropism growth
> NEGATIVE Phototropism
> POSITIVE Hydrotropism
> POSITIVE Gravitropism = grow down
What happens at Shoots?
Tropisms
> NEGATIVE Gravitropism = grow up
> NEGATIVE Hydrotropism
> POSITIVE Phototropism
Where are auxin produced?
Apical meristem
TOP of plant
What happens when there is HIGH levels of auxin?
> Stimulate SHOOT growth
> Inhibits ROOT growth
What happens in a plant cell when Phototropism occurs?
1- Auxin diffuse to shaded side of plant (no light)
2- Unequal auxin distribution = cell elongation towards light
> Heavy auxin = plant bends one way
3- Once light falls EQUALLY on all sides of shoot = auxin redistribute EVENLY
