Plant Hormones Flashcards
What is an auxin
A plant growth hormone
Where abouts are auxins in plants
Near the tips of the roots and shoots
In response to what does the auxin control growth of the plant
Light - phototropism
Gravity - gravitropism or geotropism
Moisture
What direction does auxins move and why
Backwards to stimulate the cell elongation (enlargement) process which occurs in the cell behind the tips
What happens if the tip of a shoot is removed
No auxin is available and the shoot may stop growing
Where does the extra auxin promote growth and where does it not
It promotes growth in the shoot but inhibits growth in the root - producing the desired result
Shoots grow towards….
The light
What happens when a shoot tip is exposed to light? And what does this mean
More auxin accumulate on the shaded side than the side in the light.
This makes the cell grow (elongate) faster on the shades side so the shoot bends towards the light
What do shoots grow away from
Gravity
What happens when a shoot is growing sideways and
Gravity produces and unequal distribution of auxin in the tip, with more auxin on the lower side
This causes the lower side to grow faster and bend upwards
What do roots grow towards
Gravity
Where do the auxins on the root growing sideways accumulate?
On a root growing sideways it will always have more auxin on its lower side
How does the extra auxin affect the root
The extra auxin inhibits growth. This means he cell on top elongate faster and the root will bend downwards
What else do roots grow towards
Moisture
How does moisture affect how a root grows
An uneven amount of moisture either side of the root produces more auxin on the side with more moisture. This inhibits growth on that side , causing the root to bend in that direction , towards the moisture
