B5 Plant Hormones

Question 1

Explain what is it

Auxin

Answer 1

Controls growth near the tip of shoots and roots.
It controls growth in response to light and gravity.

Auxin is produced in the tips and moves backwards to stimulate cell elongation which occurs in the cells just behind the tips.

If the tip is removed, no auxin is available and the shoot may stop growing.

Extra auxin promotes growth in the shoot but inhibits growth in the root.

Question 2

Gravitropism
Phototropism

Answer 2

The growth of a plant in response to gravity. Roots show positive gravitropism (grow towards gravity), while shoots show negative gravitropism (grow against gravity).

The growth of a plant in response to light. Shoots show positive phototropism (grow towards light), while roots may show negative phototropism (grow away from light).

Question 3

3 uses of Auxin commercially

Answer 3

Killing weeds
Rooting powder for plant cuttings
Growing cells in tissue culture

Question 4

Explain what it is

Giberillin and its 3 uses

Answer 4

Stimulates seed germination/Stem growth and flowering.
Growing larger fruit
Inducing flowers-Flower without change in enviroment
Controlling Dormancy-Seeds won’t germinate until they’ve been through certain conditions.

Question 5

Whats does ethene do and how is it produced

Answer 5

Produced by aging parts of the plant. It stimulates ripening of the fruit. Meaning fruits can be picked when unripe and ethene can be used to ripen them.