Topic 5 Plant Hormones Flashcards
What is the plant hormone
Auxin
What does auxin do
Controls growth at the tip of shoots and roots
Controls the growth of the plant in response to light (phototropism) and gravity (geotropism)
Where is auxin produced
In the tips and moves backwards to stimulate Elongation process which occurs in a cells just behind the tips
What happens if the tip of a shoot is removed
No auxin is available and the shoot may stop growing
What does extra auxin promote
Growth in the shoot but inhibits growth in the root
Where does auxin accumulate if a shoot tip is exposed to light
On the side that is in the shade
What happens when auxin accumulates on the shaded side
The cells elongate faster on the shaded side so the shoot bends towards the light
What happens when a shoot is growing sideways
Gravity produces an unequal distribution of auxin in the tip with more auxin on the lower side
This causes the lower side to grow faster bending the shoot upwards
Where is the more auxin if a root is growing sideways
On its lower side
What does extra auxin do in a root
Inhibits growth meaning of cells on the top elongate faster and bends the root downwards
Investigate plant growth responses practical
1) put 10 cress seeds into three different petri dishes lined with moist filterpaper
2) Set a light on to one of the dishes from four and two of the dishes from different directions
3). Leave for a week and see their responses

What are the control variables
Number of seeds
type of seed
temperature
water
light intensity
