20 - Plasticity Flashcards
What does plasticity mean?`
Plasticity is the ability of a plant to change its phenotype in response to changes in the environment in order to adapt to it better.
What is phototropism?
Phototropism is when the plant tip grows towards the light.
Which hormone is responsible for phototropism?
Auxin (indolacetic acid)
Which protein absorbs blue light in phototropism?
Phototropin
What happens to auxin when blue light is absorbed?
Auxin is moved to to the dark side of the plant, which stimulates growth on this side, bending the stem towards the light.
What can be done to plants to remove apical dominance?
Prune them
Which would have stronger apical dominance: saplings in dense forest or plants growing in open areas?
Saplings in dense forest - they grow straight up towards the light
How do plant roots use auxin?
Plant roots use auxin to grow away from the light and stay in the soil.
Where is auxin produced?
In the leaf primordial cells at the shoot apical meristem
How is auxin transported?
Through vascular parenchyma cells / phloem
Where is Gibberellin produced?
In young shoot tissues - apical meristems, young leaves and embryos
How is Gibberellin transported?
Through xylem and phloem
What does Gibberellin do?
It regulates cell enlargement, causing stem elongation and from growth. It also stimulates seed germination.
Where is Cytokinin produced?
In the Root tips
How is Cytokinin transported?
Through the xylem
What does Cytokinin do?
It counteracts apical dominance, as well as controlling cell division and differentiation and delays the ageing of leaves.
Where is Abscisic acid produced?
In mature leaves, stems and roots, and in green fruit
How is Abscisic acid transported?
In the roots - through xylem
In the leaves - through phloem
What does Absiscic acid do?
It causes seed dormancy and regulates plant responses to drought (closing stomata)
A wild, ripened banana appears
Ethylene!
Where (and when) is ethylene produced
In most tissues when the plant experiences mechanical stress
How is ethylene transported
As it is a gas, it just diffuses through the plant
What does ethylene do?
It ripens green fruit, it is a stress response, responding to touch/wind by ceasing length growth and causing stems to grow thicker and horizontally
What does a eucalyptus do when its apical dominancy is destroyed in a bushfire?
It releases buds from their trunk, and new sprouts will assume dominancy. The tree will get a new leading shoot.
