Growth promoters

Question 1

Give an example of a growth promoter in a plant

Answer 1

Auxins are examples of growth promoters in plants.

Question 2

What is an auxin

Answer 2

a growth promoter

Question 3

Define growth promoter

Answer 3

A growth promoter is a chemical that causes increased growth in plants

Question 4

what is the most important auxin?

Answer 4

There are a number of auxins, the most important of which is indoleacetic acid (IAA).

Question 5

What does IAA stand for?

Answer 5

indoleacetic acid (IAA).

Question 6

What is IAA simply called?

Answer 6

auxin

Question 7

Where is IAA made? (general)

Answer 7

is made in shoot tips, young leaves and seeds.

Question 8

How does IAA move down the stem?

Answer 8

It moves down the stem by an unknown mechanism.

Question 9

What do auxins cause in plants? What is this specific to?

Answer 9

Auxins cause stem and root growth and stimulate fruit formation (at certain concentrations).

Question 10

Where is IAA/auxin made specifically?

Answer 10

Auxin is produced in the meristematic tissue in the tips of shoots. It is also produced in young leaves and in developing seeds.

Question 11

Name the functions of auxin (7)

Answer 11

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.

Question 12

What is the effect of auxins in terms of tropism?

Answer 12

Tropisms:
Auxins cause cell elongation and growth or bending,

Question 13

What part of the plant is the apex?

Answer 13

The apex is the tip (top) of the plant.

Question 14

Apical dominance: If the apical bud is intact, what will the auxin that is produced, do?

Answer 14

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.

Question 15

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?

Answer 15

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).

Question 16

Apical dominance: what happens if the apical tip is removed?

Answer 16

If the apical tip is removed side branches are allowed to develop. The plant will then develop as a low, bushy form.

Question 17

Why do farmers often cut down hedges?

Answer 17

Farmers often cut down hedges to stimulate slide branching and form a livestock proof barrier

Question 18

Is IAA made in developing seeds?

Answer 18

IAA is made in developing seeds.

Question 19

Why is IAA is made in developing seeds?

Answer 19

It stimulates food to form in the fruit that surrounds the seed(s).

Question 20

What does IAA do at low concentrations?

Answer 20

At low concentrations, IAA causes roots to grow

Question 21

What does IAA do at higher concentrations?

Answer 21

at higher concentrations IAA causes stems to grow

Question 22

What can IAA do when being applied artificially to plants? What is better at this though?

Answer 22

IAA can be applied artificially to stimulate rooting. However, commercially prepared growth promoters (i.e. synthetic ones) are more efficient at this process.