Plant responses: Roles of Plant Hormones + their
Commercial uses
Survive + reproduce so can pass on alleles to their offspring
Plant Responses
Respond to abiotic (non-living = light, water…) + biotic (living =
bacterial/fungal pathogens, herbivores…) stimuli (changes in environment)
Chemical Responses to Herbivory
Reduces effects of herbivores on them…
Tannins – Toxic to herbivores + microorganisms + taste bad
Alkaloids – Toxic to insects + taste bitter
Pheromones- released into air (attract insects to flowers so they can pollinate
them) vulnerable to herbivory (act as alarm to warn neighbouring plants); can
be stimulus to other plants; these plants then respond by producing (own
defence) tannins etc…
Touch Response to Herbivory
Mimosa Pudica – Leaf folding; causes insects to drop off; causes
herbivores to be alarmed.
Plant Responses – Tropisms
Tropisms – directional response to abiotic stimulus (direction of
stimulus/away from direction of stimulus)
Positive Tropism – Moves towards stimulus
Negative Tropism – Moves away stimulus
Commercial uses
Survive + reproduce so can pass on alleles to their offspring
Plant Responses
Respond to abiotic (non-living = light, water…) + biotic (living =
bacterial/fungal pathogens, herbivores…) stimuli (changes in environment)
Chemical Responses to Herbivory
Reduces effects of herbivores on them…
Tannins – Toxic to herbivores + microorganisms + taste bad
Alkaloids – Toxic to insects + taste bitter
Pheromones- released into air (attract insects to flowers so they can pollinate
them) vulnerable to herbivory (act as alarm to warn neighbouring plants); can
be stimulus to other plants; these plants then respond by producing (own
defence) tannins etc…
Touch Response to Herbivory
Mimosa Pudica – Leaf folding; causes insects to drop off; causes
herbivores to be alarmed.
Plant Responses – Tropisms
Tropisms – directional response to abiotic stimulus (direction of
stimulus/away from direction of stimulus)
Positive Tropism – Moves towards stimulus
Negative Tropism – Moves away stimulus
