Growth promoters Flashcards
Give an example of a growth promoter in a plant
Auxins are examples of growth promoters in plants.
What is an auxin
a growth promoter
Define growth promoter
A growth promoter is a chemical that causes increased growth in plants
what is the most important auxin?
There are a number of auxins, the most important of which is indoleacetic acid (IAA).
What does IAA stand for?
indoleacetic acid (IAA).
What is IAA simply called?
auxin
Where is IAA made? (general)
is made in shoot tips, young leaves and seeds.
How does IAA move down the stem?
It moves down the stem by an unknown mechanism.
What do auxins cause in plants? What is this specific to?
Auxins cause stem and root growth and stimulate fruit formation (at certain concentrations).
Where is IAA/auxin made specifically?
Auxin is produced in the meristematic tissue in the tips of shoots. It is also produced in young leaves and in developing seeds.
Name the functions of auxin (7)
Functions of auxin:
1. The functions of auxin include:
2. Stimulating stem elongation
3. Stimulating root growth
4. Causing cells to form into different structures (eg. in the zone of differentiation in the root)
5. Developing fruit
6. Inhibiting side branching in stems Causing phototropism
7. Causing geotropism.
What is the effect of auxins in terms of tropism?
Tropisms:
Auxins cause cell elongation and growth or bending,
What part of the plant is the apex?
The apex is the tip (top) of the plant.
Apical dominance: If the apical bud is intact, what will the auxin that is produced, do?
If the apical bud is intact, auxin produced in the tip will pass down the stem and inhibit (prevent the growth of) lateral buds and any side branching.
If the apical bud is intact, auxin produced in the tip will pass down the stem and inhibit (prevent the growth of) lateral buds and any side branching. What plant is this seen in?
This form of growth is clearly seen in cacti (which have very few side branches) and conifers (where the inhibition decreases down the stem, allowing lower branches to grow more strongly).
Apical dominance: what happens if the apical tip is removed?
If the apical tip is removed side branches are allowed to develop. The plant will then develop as a low, bushy form.
Why do farmers often cut down hedges?
Farmers often cut down hedges to stimulate slide branching and form a livestock proof barrier
Is IAA made in developing seeds?
IAA is made in developing seeds.
Why is IAA is made in developing seeds?
It stimulates food to form in the fruit that surrounds the seed(s).
What does IAA do at low concentrations?
At low concentrations, IAA causes roots to grow
What does IAA do at higher concentrations?
at higher concentrations IAA causes stems to grow
What can IAA do when being applied artificially to plants? What is better at this though?
IAA can be applied artificially to stimulate rooting. However, commercially prepared growth promoters (i.e. synthetic ones) are more efficient at this process.
