Module 5 - plant responses Flashcards
(40 cards)
What is plant responses?
plants respond to changes in their environment in their environment to manage their chances of survival, e.g. towards the light to increase rate of photosynthesis
what is tropism?
the response to a plant to a directional stimulus
what are growth hormones?
- Plants response to stimuli using growth hormones
- as they have a circulatory system or a nervous systems like humans
What are auxins (IAA)?
they cause cell elongation in shoots (not cell division)
what are gibbrellins?
- they responsible for controlling flowering and germination
what are common about all growth hormones?
they are made in the growing regions of the plants - root tips and shoot tips
how do growth hormones move short distances?
- move short diffusion by diffusion and active transport
where do growth hormones move long distances?
in the phloem
what happens in phototropism?
IAA moves to the shaded side of the shoot/root
what happens in geotropism?
IAA always move to the underside
In shoots, what happens in phototropism?
IAA causes cell elongation, shoots grow towards the light
In roots, what happens in phototropism?
IAA inhibits cell growth -> roots grow towards the light
In shoots, what happens in geotropism?
- grow way from gravity, - - - cell elongation
- negative geotropism
In roots, what happens in geotropism?
- grow towards gravity
- Positive geotropism
Plant responses to herbitory - what happens when chemical are released?
- bitter/bad tasting
-toxic
Plant responses to herbitory - example of a chemical
- Tannins -> toxic -> Inhibit enzyme in insects
- Alkeloids e.g. caffeine and cocaine
- attract herbivores - attract wasps to eat caterpillars
Plant responses to herbitory - give examples of sting or thornes
e.g. stinging nettles such as roses
Plant responses to herbitory - how does folding leaves work?
- folds leaves in half quickly
- dislodge small insect herbivores
Plant responses to herbitory - example of folding leaves?
mimosa
explain the steps of apical dominance?
- Apical bud at the top of the stem produces auxin e.g. IAA
- auxins promote growth at the apical bud
- auxin inhibits growth of the lateral buds
- plant grows taller and doesn’t compete with itself
- apical bud is dominant over lateral bud
- auxin concentration decreases with distances from apical bud -> lateral buds further from apical bud are less inhibited
what happens if we remove the apical bud?
-if the apical bud is removed, less auxin is made
- lateral buds are not inhibited
-> start to develop
- becomes bushy
- if auxin is added to top of of cut stem
- apical dominance continues
what are an example of auxins?
IAA
Give an example of gibrellins ?
Gibbrellic acid
where are auxins made?
- root tips
- shoot tips
- young leaves
- growing parts of the plants
