plant hormones Flashcards
1
Q
state 3 reasons that plants are dynamic systems
A
- photosynthesis
- produces food
- responds to environmental stressors
2
Q
what are the key limitations of plants?
A
- rooted (not mobile)
- don’t have a rapidly responding nervous system
3
Q
what is the general role of plant hormones?
A
produced in one region of the plant, transported through transport tissues between cells, have an effect in another plant region
4
Q
state 2 reasons that plants produce chemicals
A
- protect themselves against insects
- chemical defence against herbivores
5
Q
state 4 examples of plant hormones
A
- auxins
- ethene
- giberellins
- abscisic acid
6
Q
describe the role of auxins
A
- causes cell elongation in stems
- inhibits growth in roots
- prevents leaves dropping
- maintains apical dominance
7
Q
describe the role of ethene
A
- gas that causes fruit to ripen
8
Q
describe the role of giberellins
A
- stimulates seed germination, stem elongation and pollen tube growth in fertilisation
9
Q
describe the role of abscisic acid
A
- stimulates stomatal closing
- maintains dormancy of seeds
10
Q
state 3 commercial uses of plant hormones
A
- control fruit ripening
- rooting powders
- hormonal weed killers
11
Q
describe ‘control of fruit ripening’
A
- ethene is used to speed up ripening of fruit
- restricting ethene can also delay ripening
- low o2, high co2 and low temp prevent ethene synthesis
12
Q
describe ‘rooting powders’
A
- synthetic auxins are used in rooting powders
- they stimulate the growth of roots from cut stems
- they are used to encourage cuttings to make roots
13
Q
describe ‘hormonal weed killers’
A
- synthetic auxins used
- kill broad leaved weed in fields of monocots
- increases growth rate of weeds
- weeds are unable to absorb nutrients and energy from surroundings to keep up with the growth rate so they die
14
Q
what is the experimental evidence for the role of auxins?
A
- auxins produced in the plant apex inhibit growth from lateral buds
- if the tip is removed, the plant grows from the buds
- this is known as apical dominance
15
Q
summarise the experiments for roles of auxins
A
- auxin paste was applied to a cut shoot and lateral buds did not grow
- auxin transporter was applied below apical tip and this allowed natural growth which suggests that low levels of auxins allow lateral growth
- auxin conc increases in lateral buds when apical tip is removed
