Plant Responses - Module 5 Flashcards
What are 3 main uses of commercial plant hormones?
- Control of ripening
- Hormone rooting powder and micropropagation
- Hormonal weedkillers
How are plant hormones used to control the ripening of fruit?
Plants will be harvested prior to ripening so they are hard and less likely to be damaged during transport
Once ready to be sold they are exposed to ethene - the hormones that makes them ripe
How are plant hormones used commercially for micropropagation?
Adding auxins to cut shoots promotes the growth of new shoots, thus enhancing the success of propagation of new plants from cuttings
How are plant hormones used commercially in hormonal weedkillers?
As interactions between plant hormones are balanced to prevent growth, the interruption of this balance may disturb the metabolism of the plant and subsequently kill it
What hormones are used in weedkillers and what effect do they have on the plant?
Synthetic dicot auxins, impact the metabolism of a plant and they die
What is a tropism?
Plant growth response to a stimuli from one direction
What is a phototropism?
Plant growth response to light
How do phototropism’s occur?
Occur as a result of the movement of auxins across the shoot or root (if the root is exposed to light) that is stronger on one side than the other
What way will shoots grow in regard to light?
Shoots are positively phototropic and will grow towards light
What way will roots grow in regard to light?
Roots are negatively phototropic and will grow away from the light
What plant hormones controls stomata control?
ABA hormone causing stomata to close
Why do plant hormones control the stomata?
To open the stomata to cool the plant and close the stomata in order to conserve water
What is a specific response of the mimosa pudica?
Plants folding in response to touch
- potassium ion movement and osmotic water movement allow the leaves to curl and unfold scaring herbivores and dislodging insects
What do tannins do as a plant chemical defence?
Tannins are toxic to insects as well as contain a phenol compound which is bitter
What do alkaloids do as a plant defence chemical?
Contain bitter nitrogenous compounds and are toxic to animals acting as poison