16.1 Plant Hormones And Growth In Plants Flashcards
1
Q
What is a tropism?
A
A directional growth in response to environmental cues such as light and gravity
2
Q
What do auxins do?
A
- control cell elongation
- prevent leaf fall (abscission)
- maintain apical dominance
- involves in tropisms
- stimulate the release of ethene
- involved in fruit ripening
3
Q
What does gibberellin do?
A
- cause stem elongation
- trigger mobilisation of food stores in a seed germination
- stimulate pollen tube growth in fertilisation
4
Q
What does ethene do?
A
- cause fruit ripening
- promotes abscission in deciduous trees
5
Q
What does ABA (abscisic acid) do!
A
- maintains dormancy of seeds and buds
- stimulates cold protective responses e.g antifreeze production
- stimulates stomatal closing
6
Q
What is the process of seed germination?
A
- seed absorbs water which activates the embryo and begins to produce gibberellins
- gibberellins stimulate the production of enzymes that break down the food stores found in the seed
- food store is in the cotyledons in dicot seeds and the endosperm in monocot seeds
- embryo plant used these food stores to produce ATP for building materials so it can grow and break out through the seed coat
- gibberellins switch on genes which code for amylase and protease (digestive enzymes required for germination)
- ABA acts as an antagonist to gibberellins
The relative levels of both hormones determine when the seed will germinate
7
Q
What is an “antagonist”?
A
Something which interferes with the action of another hormones
