Controlling Plant Growth Flashcards
Give four examples of hormones that control plants
- Auxins
- Ethylene
- Gibberellins
- Cytokinins
What are plants controlled by?
Hormones
What is phototropism?
Phototropism is growth in response to light
What is geotropism?
Geotropism is growth is response to gravity
What is positive phototropism?
The plant growing towards light
What is positive geotropism?
The plant is growing towards gravity
What is negative phototropism?
The plant is growing away from light
What is negative geotropism?
The plant is growing away from gravity
When is auxin produced?
At the tip and it diffuses backwards to stimulate cell elongation process which occurs in the cells just behind the tips
What does auxin do?
Auxin promotes growth in the shoot, but actually inhibits growth in the root
Explain positive phototropism?
Auxin collects on shaded side making cells elongate
Explain positive geotropism
Auxin collects on bottom side making cells grow less
Explain negative phototropism
Auxin collects on shaded side making cells divide less
Explain negative geotropism
Auxin collects on bottom side making cells grow more
Plants use hormones commercially as:
- Selective weed killers
- Rooting powder
- Fruit ripening (delay or acceleration)
- Control of dormancy
What are the type of leaves most weeds grow in fields?
Broad leaves
What commercial use can affect broad leaves?
Selective weed killers. The disrupt their normal growth patterns, which soon kills them, whilst leaving the grass and crops untouched
What is the name of the part of the plant that has been cut off?
Cuttings
What do you add to make a cutting grow?
Rooting powder
What do cuttings allow the farmers to do?
They allow the farmers to produce a lot of clones
What is it useful to use plant hormones to delay ripening?
Because it’s easier to transport
What is a seed that won’t germinate until it experiences certain conditions called?
Dormancy
What hormone allows the seeds to germinate?
Gibberellin
Why is gibberellin useful for commercial growers?
Because commercial growers can treat seeds with gibberellin to make them germinate at times of year when they wouldn’t normally. It also helps to make sure all the seeds in a batch germinate at the same time
