Plant Hormones Flashcards
What do hormones do?
Stimulate or inhibit activity.
What are growth regulators?
Man-made versions of hormones.
How do plant hormones bring about change?
By binding to receptors on plant cells which initiates biochemical signal transmissions.
What are biochemical signal transmissions?
Chemical reactions that bring about physiological changes.
Name some examples of plant hormones.
Auxins, gibberellins, cytokinins, abscisic acid, ethylene, brassinosteroids.
Who discovered auxins?
Frits Went.
What are auxins structurally similar to?
Tryptophan
What do we associate auxins with?
Phototropisms, fruit development, apical dominance
Where are auxins made?
Apical meristems, buds and in young leaves.
What are auxins?
Plant hormones that encourage the bending of plant tips towards the light.
What do auxins promote?
Flowering & fruiting
What do auxins inhibit?
Leaf abscission
What might auxins help regulate?
Cell elongation
What are gibberellins?
Plant hormones that stimulate growth.
Where are gibberellins made?
apical meristems, young leaves and in embryos
What are gibberellins involved in?
Cell elongation, mitosis stimulation in internodes, breaking dormancy, stem elongation and initiating flowering
Where were cytokinins first discovered?
The phloem.
What do cytokinins do?
They stimulate cell division, differentiation, cotyledon growth, lateral bud development and the production of cork cambium
Where are cytokinins found?
Germinating seeds and roots
What can cytokinins delay?
Senescence
What can cytokinins encourage?
Stomatal opening
What happens if the ratio between cytokinin and auxin is equal?
The plant will grow haphazardly.
What happens if the ratio of cytokinin is higher than auxin?
Tissue develops in the shoots
What happens if the ratio of cytokinin is lesser than auxin?
Tissue develops in the roots
