Plant and animal Responses Flashcards
What are tannins?
A chemical defence of plants
- Toxic to microorganisms and larger herbivores
- Found in the upper epidermis of leaves making them taste bad
- Found in roots to prevent infiltration by pathogens
What are alkaloids?
A chemical defence in plants
- located in growing tips and flowers -taste bitter
- derived from amino acids
What are pheromones?
Chemicals released by one individual that can affect the behaviour or physiology of another
What is phototropism?
Shoots grow towards light (positively phototrophic) allowing them to photosynthesise
What is geotropism?
Roots grow towards the pull of gravity anchoring them into the soil in order to take up water keeping them turgid
What is chemotropism?
On a flower when pollen tubes grow down the style attracted by chemicals to the ovary
What is thigmotropism?
When shoots of climbing plants wind around other plants or structures to gain support
What are nastic responses?
When a plant has non-directional responses to external stimuli eg thigmonasty when plant leaves fold due to touch
What happens when you break the shoot tip/apex of a plant off?
The plant starts to grow side branches from lateral buds which were previously dormant.
What did researchers suggest the effect of auxin is in the apical bud? How did they test this
A normal level of auxin from the apical bud inhibits the growth of lateral buds while low levels promote growth. To test their hypothesis they applied a paste containing auxins to the cut end of the shoot and lateral buds did not grow
How did researchers ensure that the growth of lateral buds was not due to exposure to oxygen in the apical bud?
They applied a ring of auxin transport inhibitor below the apex of the shoot. The lateral buds grew
What are giberellins?
Plant hormones responsible for control of stem elongation and seed germination
How did researchers figure out the effect of giberellins on stem growth?
Hggehehe
