Plant Responses Flashcards
Three groups of plant hormones
Auxins
Gibberellins
Abscisic acid
What type of tissues do auxins target?
Meristem tissues in roots, stems and leaves
Where are auxins produced?
Growing tips of stems and roots and in apical buds
What are the functions of auxins?
Cause tropisms in stems and roots Stimulate root growth in cuttings Promote fruit development Controls abscission Ensures apical dominance
What is abscission?
Natural detachment of parts of a plant (e.g. autumn leaves, ripe fruit)
What is apical dominance?
When only the apical bud (very tip) of a branch grows, lateral buds lie dormant as long as the apical bud is present and start to grow when apical bud is removed
Where are gibberellins produced?
Mainly in the terminal buds of stems and roots
What are the functions of gibberellins?
Stimulate stem elongation Promote root growth Promotes flowering Promotes lateral bud growth Stimulates germination of seeds
Abscisic acid is a growth _____ that _______ auxins
inhibitor; counteracts
Where is abscisic acid produced?
Leaves, stems and unripe fruit
_____ ____ helps plants deal with stressful conditions
Abscisic acid
What are the functions of abscisic acids?
Causes dormancy of buds in winter
Inhibits germination promoting seed dormancy
Promotes abscission of leaves
Causes stomata to close when a plant wilts
How are plant hormones used in weed control?
High levels of auxins are sprayed to increase weed growth to the extent that weeds weaken and die
What is tropism?
Growth response to a stimulus caused by auxins
What is the difference between positive and negative tropisms?
Positive tropisms - growth towards a stimulus
Negative tropisms - growth away from a stimulus
